本文基于隐性合同和关系银行理论,模型化银行和中小企业建立稳定信贷关系的内在机制。一方面,银行合理安排异质性信贷技术,在声誉机制下确定最优业务比例,在稳定银企关系的同时鼓励中小企业创新;另一方面,宏观经济波动不利于银行对异质性信贷技术形成合理预期,不仅造成中小企业在经济下行期间被首先排除在银行授信体系之外,而且在经济上行阶段也难以确保连续获得信贷资金,这会抑制中小企业创新。因此,宏观经济政策不仅要在经济不景气时给予中小企业适当扶持,更要在经济繁荣时通过充分的制度安排确保中小企业能在经济发展中连续受益。 Based on the implicit contracts and the theory of relational banks, this article models the internal mechanism of establishing stable credit relations between banks and SMEs. On the one hand, banks arrange heterogeneous credit technology reasonably, determine optimal business proportion under the reputation mechanism, and encourage SMEs to innovate while stabilizing the relationship between banks and enterprises; on the other hand, the macroeconomic fluctuations are not conducive to the bank’s influence on heterogeneous credit technologies The formation of a reasonable expectation will not only result in SMEs being excluded from the bank credit system during the economic downturn, but also failing to ensure continuous access to credit funds during the economic upward phase, which will inhibit the innovation of SMEs. Therefore, macroeconomic policies should not only give appropriate support to SMEs in times of economic downturn, but also ensure that SMEs can continue to benefit from economic development through sufficient institutional arrangements during economic boom.