Mortgage prepayment not only increases the difficulty of matching commercial bank assets and liabilities but also has a negative impact on its future earnings. Therefore, necessary compensation should be provided. Based on the decisions made by borrowers and commercial banks, this paper establishes constrained optimization model and respectively analyzes the relationship between the mortgage prepayment default rate and prepayment rate in the case of floating rate and fixed rate. The study finds that in the floating rate and fixed rate mortgage market supply and demand curves generally comply with the laws of supply and demand in general commodity markets, but the slopes of the supply curve and demand curve in diverse markets are different. Accordingly, the general equilibrium analysis framework of mortgage prepayment market should be constructed. Then it is possible to analyze the equilibrium solution to maximum social welfare and the welfare loss when the market deviates from equilibrium.