Abstract: The paper designs a new structure of weapons bay door actuation system based on the layout characteristics and weight reduction requirements of large unmanned combat aircraft, the system can save the inside space of weapon bay and reduce the weight of the system effectively. Innovatively integrating the differential gear mechanism in the system enables the system to achieve separate or synchronous movement of the left and right doors according to different commands, while designing emergency control oil circuits inside it to improve system task reliability. By using AMESim simulation platform, motion simulations were conducted on the system in various working modes. The simulation results show that the new structure of weapons bay door actuation system can meet the functional performance requirements, laying a theoretical foundation for subsequent engineering applications.