In view of the difficulty of financing for SMEs, this paper puts forward a conceptual model and relevant hypothesis of the stability of cooperative relationship in supply chain and the positive impact of credit diffusion of core enterprises on the financing performance of SMEs under the supply chain financial model from the perspective of signaling mechanism and industrial symbiosis theory, empirical research is carried out by using the panel data of GEM listed companies from the year 2011 to 2017. The results show that the cash holdings of enterprises will change positively with their operating cash flows, which indicates that enterprises can’t obtain sufficient funds from outside and face a certain degree of financing constraints. After adding the variable of supply chain financial development level, the cash holdings of enterprises will be weakened by their operating cash flows, indicating that the degree of financing difficulties will be reduced. Based on this, this paper introduces the stability of cooperation relationship in the supply chain and the credit impact of core enterprises as two adjusting variables. The interaction item is added into the original model to make overall regression, and then tested by grouping. It is found that the supply chain financial model can be applied to enterprises whose cooperation relationship tends to be stable in supply chain and enterprises whose credit is diffused by core enterprises. It has a more significant mitigation effect of financing constraints, which makes the hypothesis of this paper verified.