Abstract: In order to optimize the overall trustworthiness of supply chain, the theory of supply chain was analyzed, and the characteristics of credit relationship of supply chain, i.e. relevance, path dependence and heterogeneity was elaborated; then the credit relationship of supply chain was divided into direct credit and indirect credit. Based on these analyses, the framework to optimize the credit relationships of supply chain was also constructed with methods of evolution stable strategy (ESS) and replicator dynamic,and a measurement of credit weight for supply chain partners was given based on AHP with the criteria of logistics, information flow, capital flow. Finally, the evolutionary method of supply chain trustworthiness improvement was proposed, and the proof for the rationality of this policy with induction was provided.