Robot technology is being broadly applied in medical area. Assistant microsurgery robot is an important branch of medical robot. This paper introduces the architecture of a robot assistant microsurgery system (RAMS) which is developed by University of Nankai and explains the design of the control software of the system. The architecture of electrical and electronic control sub-system of the robot assistant microsurgery system is emphasized and detailed in this paper. Moreover, some clinical experiment results of microsurgery on animals are reported which demonstrate that the RAMS satisfies the requirements of assistant microsurgeries with a high moving precision and high working reliability