The basic contradiction of capitalism is the contradiction between socialization of production and private possession of means of production. The subprime mortgage crisis in the United States is mainly due to the crisis caused by subprime mortgage. Loans are graded. Generally, banks will not give large loans to subprime credit, but the United States makes more profits in order to promote the liquidity and liquidity of capital. However, due to the inability of these lenders to repay their loans, the capital chain is broken and normal financial behavior cannot be carried out. Most of the subprime loans issued by the United States were purchased by European countries, which caused the current economic recession in European countries.