Credit card system has become an important part of financial electronization in China. It has profoundly changed people's financial concept and social payment system with its fast, convenient and safe features. The credit card business processing system mainly includes credit card trading center, issuing bank processing center, bank savings outlets, ATM outlets and POS system. This paper mainly discusses the function of credit card trading center. The credit card transaction center is connected with the following entities: the card-issuing bank processing center, the ATM/POS connected with the card-issuing bank, the remote credit card transaction center and the international credit card authorization network. First, the authorization transfer function authorization is simply the transaction license obtained by the cardholder from the issuing bank. The work done by the authorization processing system is to process the transaction request first (including information format conversion, information encryption and decryption, cardholder parameter verification, agent processing, etc.). ), and then forward it to the transaction destination entity according to the transaction category, card number and information content, and ensure the integrity and validity of the information. The authorization system of the credit card trading center shall provide the following authorization transfers: between the acquiring institution and the issuing bank, between the acquiring institution and the remote credit card trading center or the national credit card trading center, between the acquiring institution and the international authorization network, between the remote credit card trading center or the national credit card trading center and the issuing bank, between the international authorization network and the issuing bank, and between the ATM/POS machine directly connected with the credit card trading center and the issuing bank. Authorization transfer between ATM/POS machines directly connected to credit card exchange center and remote credit card exchange center and between ATM/POS machines directly connected to credit card exchange center and international authorization network. For example, the authorized transfer between the acquiring bank and the remote transaction center or the national credit card transaction center can be represented by the following figure. POS/ATM is an important means and tool for cardholders to obtain services through credit cards, so it plays an important role in the whole credit card authorization service system. The POS/ATM machine can be directly connected to the credit card transaction center or to the host of the bank POS/ATM system. Cardholders can also use POS/ATM machines in different places, or use POS/ATM machines abroad with foreign exchange cards. At this time, the authorization transfer process is completed by the POS/ATM authorization processing system. Generally speaking, the POS authorization processing system should support three inter-bank transaction functions: authorization request, authorization revocation and balance inquiry. ATM authorization processing system should generally support the following inter-bank transaction functions: withdrawal, deposit and balance inquiry. Although their functions are different, their business processes are basically the same. They all insert the card into the ATM/POS machine to start the transaction, and send the transaction request information directly or through the credit card network to the information exchange center, which will process the authorization request to a certain extent and forward it to the issuing bank. The issuing bank checks and sends back the authorization request response information to the trading center, which sends it to ATM/POS through the original channel. After receiving the authorization response information, the relevant accepting bank sends a confirmation message to the trading center, and the trading center sends the confirmation message back to the issuing bank. The switching center can also undertake the function of agent authorization. When the issuing bank cannot handle the authorization, for example, the issuing bank's host computer fails or is doing routine maintenance work, and the authorization request sent by the credit card transaction center cannot be received, or the network between the issuing bank and the transaction center is blocked, and the authorization request cannot reach the issuing bank, or the issuing bank exceeds the scheduled response time or the transaction amount is low-risk. , the credit card trading center must be able to respond to authorization instead of the issuing bank, that is, authorize on behalf of the issuing bank. The agent authorization system can complete the functions of checking the payment stop list, approving or refusing authorization according to the preset parameters of the issuing bank, processing by the issuing bank, checking the personal password and so on. Authorization transfer is one of the most important functions of credit card trading center, and it is also a key step in credit card business process. Second, the management function of the stop payment list "stop payment list" is a risk management measure to protect the interests of cardholders, acquirers, card issuers and special merchants. Stop payment list management can be located in the issuing bank or exchange center to provide tools for special merchants to identify lost, stolen or improper card use. The stop payment list is regularly updated to a convenient file for all cardholders designated by the issuing bank as "receiving cards". The content of stop payment list management includes card number, effective date, revocation reason, action code and other information. The credit card trading center updates the stop payment list file at any time and sends the stop payment list to the local bank and the national credit card trading center. The credit card trading center receives the payment stop list sent by card issuers, national credit card trading centers and international credit card organizations, and immediately merges it with the local payment stop list file. The credit card trading center will also send a stop payment list to local banks and the national credit card trading center. Stop payment list must be sent to the bank regularly, and the effective date of the list must be indicated, and then the bank will print and distribute it to the special merchants. When the issuing bank updates the documents in the city center, the city information center can immediately send them to the national credit card exchange center to update the national stop payment list. The authorization system in the credit card trading center should be able to directly check the documents of the stop payment list in order to respond to the authorization requirements of those cards that have been included in the stop payment list. Three. Clearing and settlement system function Credit card trading center provides clearing services for banks in the region, and provides domestic and international clearing services for banks through cooperation with credit card trading centers in various countries, remote trading centers and international credit card organizations. Liquidation generally includes three continuous processes: sorting, settlement and fund allocation. First, the bank extracts the transaction data, that is, the business data of other banks are transmitted to the credit card exchange center at a specified time, which verifies and confirms those transactions that do not meet the standards, and then sorts them out, that is, the exchange center distributes the transaction data transmitted by the sending bank to the receiving bank and credit card network in different places. Settlement is to determine the net difference of business data between participating banks and generate a settlement report. After sorting, the center will merge the transaction data of local banks with the transaction data sent back by the remote network, count the net difference of each bank on that day, and provide the inter-bank fund transfer data to the local and remote payment systems (namely the clearing system of the People's Bank of China). According to the daily net settlement data report provided by the Center, the bank makes settlement through the People's Bank of China. The bank negotiates with the People's Bank of China to carry out the actual capital operation between banks. Four. Risk management function A perfect credit card transaction center system should not only have efficient transaction processing function, but also have a set of flexible and accurate risk management mechanism in line with the actual environment. The exchange center can collect all kinds of transaction data, so as to use the most advanced statistical model to establish a comprehensive risk management system for anti-counterfeiting cards, anti-theft and predicting suspicious merchants and cardholders, and send relevant information to banks in time to prevent fraud and protect the interests of issuers, acquirers, special merchants and cardholders. The risk management function includes the following contents: (1) Card verification function: verify whether the credit card is a fake card or a fake card, or whether the magnetic tape data has been password-modified, so as to reduce the risks brought to the bank and protect the interests of cardholders and special merchants. (2) Personal password verification: mainly for transactions that require the use of personal passwords (PIN), such as ATM or debit card transactions. After PIN verification, the exchange center can send the authorization request to the issuing bank or handle it on its behalf according to the requirements of the issuing bank. (3) Suspicious transaction statistics and forecasting service: this is a risk monitoring service. With the help of the network, the exchange center compares the collected information about suspicious cardholders with the data of clearing and settlement services to determine the merchants who accept these suspicious cardholders' transactions, and then compares it with the "rejection" documents and the documents confirming fraudulent transactions in the system to obtain a risk pre-statement and send it to the bank so that the bank can take action to prevent fraud. (4) Suspicious merchant inquiry service: The information exchange center should collect information of all special merchants who have committed fraud in credit card transactions for banks, so that acquiring banks can conveniently and quickly understand the credit background of merchants when promoting acquiring business to merchants, and prevent or not sign contracts with them. V. Other functions The credit card trading center provides a log function, which records all authorized transactions, system performance and documents sent and received by banks, and makes statistics to estimate future demand. Transactions recorded by the trading center can handle controversial transactions. The trading center also provides liquidation report, risk management report, service quality report, business statistics report and transaction inquiry report. In addition, the credit card trading center can also consider adding some other additional functions. For example, it can provide card issuing services for banks that lack automated cards and processing systems, and it can also provide acquiring services for some banks, process transaction data sent back by special merchants, and arrange liquidation on behalf of banks. The trading center can also provide credit inquiry function. The center collects credit-related information of cardholders of various card issuers, provides inquiry services to card issuers, and helps card issuers to evaluate credit management and repayment ability of new cardholders. It can also provide credit cards and business data to the government for reference by using the stored information. A fully functional and sound credit card trading center is very important to the development of China's credit card system and plays a positive role in promoting the improvement of China's current payment system.