Abstract: Knowledge transfer from client to contractor is the key to the improvement of contractor's innovation ability and performance, but the process and mechanism are not clear. A relationship model was constructed to reveal the impact of organizational control mechanism on knowledge transfer process, in which knowledge transfer process was divided into three stages: knowledge acquisition, knowledge application and knowledge internalization. Then the joint effect of external organization control mechanism（including contract flexibility and relationship norms）and internal organization control mechanism（including knowledge sharing and integration mechanism）on the knowledge transfer process was explored. The data of 80 IT outsourcing enterprises in China Were used as samples, to empirically test several proposed hypotheses by applying the multiple hierarchical regression method. The results show that contract flexibility and relationship norms positively affect organizational knowledge acquisition; knowledge application is positively correlated with knowledge acquisition and knowledge internalization. Furthermore, knowledge sharing and knowledge integration mechanism play a regulating role in the process of knowledge transfer: knowledge sharing mechanism promotes knowledge application, and knowledge integration mechanism enhances the degree of knowledge internalization.