The existing research is generally believed that relation resources can significantly promote cooperation performance in the process of cluster enterprise cooperation, but the path is not clear and lack of empirical evidence. Based on the sample data of related enterprises in jiangsu and zhejiang industrial cluster, the paper constructed a multiple mediation effect model including relation ability and interfirm trust, tested mediation effect and verified hypothesis by using the structural equation model. Results show that the overall relation resources can significantly promote cooperation performance but the direct effect is not obvious. During this process, relation ability has played a partial intermediary role and interfirm trust has played a entire role in the meanwhile. To some extent, this also explains why some cluster enterprises’ cooperation performance vary widely while they facing the same relationship resources. This paper argues that building and sustaining relation ability which is based on trust has a decisive influence on cooperation performance in long-term.