Legal analysis: 1. Asking about the purpose of the loan and examining the legality of the loan; If the purpose of the loan is illegal, ask and verify whether the creditor knows the purpose of the borrower's loan. 2. When the loan voucher does not stipulate the loan term, it is necessary to ask whether the two parties have verbally agreed on the loan term, especially when the lender claims overdue interest. 3. Check the interest agreement. When there is a written agreement on interest, ask if there is an oral agreement on interest. On the one hand, the state has mandatory provisions on the interest of private lending, on the other hand, it involves the parties' claims on capital interest and overdue interest. According to the regulations of the People's Bank of China, the loan interest rate is three times the loan interest rate of the same grade (excluding floating) of financial institutions allowed by law.

Legal basis: Civil Code of People's Republic of China (PRC).

Article 680 usury is prohibited and the loan interest rate shall not violate the relevant provisions of the state.

If there is no agreement on the payment of interest in the loan contract, it shall be deemed that there is no interest.

If the loan contract does not specify the payment method of interest, and the parties cannot reach a supplementary agreement, the interest shall be determined according to the local or the parties' trading methods, trading habits, market interest rates and other factors; Loans between natural persons are regarded as interest-free.

Article 25 If the lender requests the borrower to pay interest at the interest rate agreed in the contract, the people's court shall support it, except that the interest rate agreed by both parties exceeds four times the market quotation of one-year loan at the time of the establishment of the contract.

The "one-year loan market quotation" mentioned in the preceding paragraph refers to the one-year loan market quotation issued monthly by the National Interbank Funding Center authorized by the People's Bank of China from August 20th, 20th, 20th19th.