The volume of workspace showed the flexibility of a serial robot. The workspace of the manipulator of a serial robot was researched. Firstly, the main structure of the manipulator was given and its kinematical model was proposed. Then, its kinematics analysis was taken. The manipulator’s workspace was analyzed by Monte Carlo method and the cloud picture was completed. The adaptive-divided mesh method was brought. The volume of workspace was calculated. At last, the effect of the manipulator’s structural parameters on the workspace volume was analyzed, which provided theoretical basis for the manipulator’s structural parameter optimization. 