In order to solve the problem of the real-time parameter adjustment when suppressing redundant force by the structural invariance compensation method, a mathematical model and a simulation model of a servo actuation system performance test platform were established, respectively. A decoupling control method for speed feedforward compensator was proposed, and a fuzzy controller was designed to suppress the redundant force. The inhibition effects of the three control methods including the traditional PI(proportional-integral) control, traditional PI feedforward compensation control and fuzzy PI feedforward compensation control on the redundant force of the test platform were compared. Simulation results show that the loading accuracy of the test platform can be improved by the fuzzy PI feedforward compensation control method with the most significant suppression effect on the redundant force. The effectiveness of the proposed control method was verified by the comparison between the experiments and simulations, which provides a theoretical reference for the servo actuation system test platform to loading with heavy thrust and high precision.