Abstract: Aiming at the automatic rocket-attaching problem of the auto-docking and auto-separating robot for launch vehicle propellant loading, a control system is designed for the automatic rocket-attaching module. The system uses image processing algorithm to provide visual information for the autonomous navigation positioning in plane, and the force servo algorithm is designed to assist the rocket-attaching to complete smoothly. A large number of docking simulation experiments and the experiments on real rockets prove the reliability and stability of the control system.