In most cases，venture capitalbacked firms tend to perform better. In the process of investment，venture capitalists(VCs) may act as a “scout”，and a “coach” as well. However, in academia，there is no agreed conclusion about whether this outperformance is mainly attributed to the preinvestment screening or postinvestment monitoring efforts of VCs. This paper presents related studying results of both the exante and expost roles of VCs and carries out a preliminary discussion，finding most of the results support VCs’ “coach” function.