Abstract: In order to solve the problem of ground microgravity simulation experiment of large space manipulator, a three-dimensional active suspension gravity compensation system is designed. The system is mainly composed of a horizontal two-dimensional linear motion unit and a vertical gravity balance suspension unit. The microgravity simulation is realized by the idea of constant tension control in the vertical direction. The mathematical model of the servo motor with load is given. A hybrid force/position control method based on fuzzy PID (proportional-integral-differential) parameter tuning is proposed. The control performance of the controller with unknown load and system interference under the different motion speeds of the manipulator is studied. The simulation results show that the control method can keep the gravity compensation accuracy within 0.3%F.S (full scale), and the system has strong robustness and dynamic response capability.