This paper presents the effect of control on knowledge transfer in service supply chain with an empirical data from China Mobile. Formal control and Social control are mechanisms usually taken to promote knowledge transfer by buyer in service supply chain. So, the role of formal control, social control and their complement to knowledge transfer are studied in this paper. Using the data collected from China Mobile, we found formal control is positively related to knowledge transfer, and social control is also positively related to knowledge transfer. In addition, there is a complement effect between formal control and social control to knowledge transfer. Theoretical and managerial implications are discussed.