Abstract: Payload release/separation from spacecraft is usually required in space missions, and the related dynamic performance during the release/separation process is one of the important issues that would affect the control of the spacecraft platform and the payload. This paper focuses on the multi-body dynamics during separation/release, and uses the Automatic Dynamic Analysis of Mechanical System (ADAMS) software to establish the simulation model, including the spacecraft platform, the payload, and the separation mechanism, to simulate the process of on-orbit release/separation. The results can be applied in the design of payload release/separation.