In order to examine the underlying mechanism of the three dimensions of trust among project participants on the project performance, and show the mediating role of knowledge transfer on the effect of trust on project performance. Under the logic of relational theory, hypotheses are proposed and a conceptual model is constructed. By means of 183 effective questionnaires from different areas, structural equation model are used to verify the proposed hypotheses. Results of the analyses suggest that contractual trust ,competence trust ,emotional trust of project stakeholders has significant positive effects on project performance while the degree to which trust affects project performance varies with different dimensions. And it has been proved that knowledge transfer plays a partially mediating role between each dimension of trust and project performance. These findings provide some valuable inspirations for project managers that project managers should not only put emphasis on the formation of high level trust, but also promote knowledge transfer among stakeholders to achieve great project performance.