Small and medium-sized financial institutions are relatively small financial institutions in terms of capital size, scale of deposit and loan business, and the size of employees in relation to large-scale financial institutions. Small and medium-sized financial institutions are a dynamic development concept, different periods have different measurement standards. Broadly speaking, China's small and medium-sized financial institutions refer to small and medium-sized commercial banks, which are significantly lower than those of state-owned large banks, Small and medium-sized insurance companies, credit cooperatives, finance companies, consumer credit agencies, postal savings institutions in terms of macro-control ability, asset-liability scale, credit guarantee system, network coverage, overall function and service means. The small and medium-sized financial institutions in the ordinary sense refer to the small and medium-sized commercial banks mainly located in the deposit and loan business, namely, national or regional joint-stock commercial banks, urban commercial banks, urban and rural credit cooperatives.