The essence of the entrepreneur's function lies in the innovation of firm mechanism.Taking the law of firm development as the basis and the behavior choice of the entrepreneur as the object,the paper discusses the possibly functional space that an entrepreneur plays a positive role,and inspects the actual way of behavior that entrepreneur promotes the development of the firm.The construction of firm mechanism is the course of creating the production function through entrepreneur using the existing conditions.The course possesses the construct task and realization route.The choice of the route is the key point influencing the entrepreneur's function.On the basis of the points above,an analytical model of entrepreneur function mechanism is established to promote the study of the entrepreneur's function.