A gravity balance mechanism for spatial robotic manipulator is proposed. In this design, a parallelogram linkage mechanism, pulleys and springs are utilized to accomplish the balance. As a passive structure, it needs no motors or actuators, and safety is another great highlight of the mechanism. The balance mechanism can solve the balance problem of both planar 2-link mechanism and spatial 2-link mechanism (a roll-pitch-yaw-roll 2-link mechanism) by adding a rotational degree of freedom. This is a more simple and effective method to solve the balance problem of spatial linkage system, especially the linkage system of multi-degree of freedom joint. And the mechanism can be extended to solve a multilink balance problem.