Abstract: Project Partnering is conceived as an intermediate organizational form between enterprise and market， which is loosely linked and fragile， based on the restriction and coordination of partnering contract. Because of the environmental uncertainty， partnering project should put emphasis on and rely on trust mechanism to ensure steady development of partnering. This paper systematically analyzes the motives and the connotations of project partnering and describes partnering organization characteristics from the view of social capital theory. On the basis of it， the trust of project partnering is analyzed. Finally， this paper gives some suggestions for the establishment of project partnering.