The space tethering system needs a ground test to verify the correctness of its theoretical research results. Aiming at the problem that its nonlinear dynamic model is complex and it is difficult for the ground to simulate the complex situation of space and it is not easy to carry out a full physical test, a tethered towed semi-physical simulation test device is designed. the tether retracting and tensioning part of the simulation system introduces a simulation circuit in the form of a physical object. During the dragging process, the system dynamics part is described by a mathematical model and converted into a simulation calculation model. A semi-physical simulation closed loop is constructed with the physical part. The controller of the master-slave position based on fuzzy PID is used to control the tension controller, and the simulink simulation model of the dragging process of the semi-physical test device is set up. From the simulation results, it can be seen that: 1) the tension controller meets the requirements of the tether control instruction of the semi-physical loading mechanism to simulate the passive star; 2) the design principle of the semi-physical test device is correct, and the dynamic model characteristics under different working conditions can be simulated; Assess the performance of the tether retractable device.