Fixed interest rate is a kind of interest rate stipulated by the state, which is not affected by the average social profit rate and the change of capital supply and demand in a certain period of time. The interest rate stipulated in the loan contract remains unchanged throughout the loan period. In the loan business for more than one year, the loan contract often stipulates an interest rate standard agreed by the borrower and the borrower to calculate interest, which is called the loan fixed interest rate. For example, international medium-and long-term export credit calculates interest on the money withdrawn or loan balance during the whole loan period according to the unified interest rate stipulated by the Organization for Economic Cooperation and Development when signing the contract.

The original contract interest rate refers to the loan interest rate agreed by the lender with the borrower according to the legal loan interest rate and the floating agreed range stipulated by the People's Bank of China and stated in the loan contract.

It should be noted that once the fixed interest rate is determined, the loan contract will not change during the whole loan period. In the loan business for more than one year, the loan contract often stipulates the fixed interest rate standard agreed by the borrower and the borrower to calculate the interest. With the implementation of the loan market quotation by the state, the original contract interest rate will change periodically.