Abstract: During ground simulations of on-orbit operations, the movement of a manipulator arm causes a shift in the test platform’s center of mass. The resulting time-varying disturbance torque due to gravity significantly impacts the accuracy of satellite ground simulation tests. Addressing the need for dynamic control of the test platform’s time-varying center of mass, a high-precision, robust dynamic control method incorporating real-time identification of mass properties is proposed. A dynamic model of the test platform, considering the influence of time-varying eccentric gravity torque, is established. A real-time concurrent recursive identification method for mass property parameters is developed. A dual-loop sliding mode control approach is proposed, with the outer loop tracking the desired attitude angles and the inner loop tracking angular velocity. Simulation validations of mass property identification and center-of-mass control are performed. When the manipulator arm moved under a typical on-orbit operating condition of 3(°)/s, the pre-identification error is stably below 4.1%. Based on the identified results, the platform’s attitude angle is controlled within 0.04°. Ground-based experiments are conducted, and the results show that the platform’s attitude angle could be stabilized within 0.1°. The simulation and experimental results demonstrate that the proposed center-of-mass control method can effectively eliminate the gravity disturbance torque in real-time. This approach provides a reliable experimental foundation for subsequent missions involving simulated on-orbit operations.