A novel parallel robot mechanism. 3-R2H2S, which contains preloaded Hooke joints is proposed in this paper. To study its dynamic performance, the structure of the 3-R2H2S robot is simplified. The global index of the robot’s dynamic performance is derived from the first and second order influence coefficient matrix. By varying different structural parameters, the velocity and inertial force performance indexes of the 3-R2H2S parallel mechanism are analyzed. The effect of the robot’s member size on the dynamic performance is discussed when the structural size is changed within the reachable workspace. Finally, dynamic performance atlases are drawn using a computer simulation and the optimized parameter group is found. This study provides a theoretical basis to optimize both design and dynamic performance of parallel robots.