To improve the design efficiency of medical robot arm, a virtual simulation system was built by making full use of the virtual simulation technology. First , a 3D model of the robot arm with five-freedom was built in Solidworks; and then, the model was imported into the dynamic simulation software RecurDyn for kinematics and dynamic simulation; at last, through the interface modular part of Matlab/Simulink and RecurDyn, medical robot arm control system was established by using Simulink module and coordinated simulation of five-freedom was successfully implemented .The simulation results indicate that the coordinated simulation system of the robot arm has preferable dynamic response characteristics and nicer locus-tracking ability.