Abstract： This paper describes a space robot modeling method. The main idea is to shift the moving coordinate system to the working point of the robot by following the mechanisms and joints. The robot was modelled to get the forward kinematics results and then simulated in Matlab. By analyzing the robot workspace with numerical method, the isometric view and profile of the workspace were obtained. The simulation experiments show that the mathematical modeling method is effective. The result of workspace analysis shows that the workspace is big enough without hole, which meets the demand of tracking. The motion tracking test on curve in space with the physical prototype is satisfactory.