Abstract: In order to eliminate the impact of inconsistent mechanical environments between space and the Earth on the operational accuracy of spacecraft in orbit, it is necessary to conduct micro-vibration environmental simulation for spacecraft on the ground. Therefore, a free boundary simulation system and an automatic control module for the facility and platform sections of spacecraft were established at the upper and lower ends of the spacecraft. The equilibrium coordination control algorithm for spacecraft gravity unloading process was designed and implemented by force and displacement closed-loops. In addition, through the construction of hardware setup and software programming, the on-site experiments were carried out to verify the feasibility and stability of the control system. The research may provide technical support and accumulated engineering experience for the design of gravity unloading process control systems in future spacecraft ground simulation experiments.