In view of problems such as lack of dynamism, limited research subjects, and lack of future development trends in previous studies, the paper takes small and microenterprises (SMEs) as research objects under the background of e-commerce supply chain finance. Based on the perspective of dynamic rewards and punishments, credit rewards and punishment value and time weights are embedded in the static evaluation results obtained by the traditional TOPSIS method. The Grey relative analysis method is used to reflect the development trend of enterprises’ credit and to build the traditional TOPSIS model and the credit risk evaluation model of e-commerce supply chain finance of SMEs by the improved TOPSIS method based on the dynamic perspective of rewards and punishments. Finally, the model is applied to SMEs credit risk evaluation of e-commerce supply chain finance to verify the feasibility and rationality of the model.