Abstract: In order to eliminate or alleviate the space adaptation syndrome caused by the microgravity during manned spaceflight and to satisfy the physical exercise needs of astronauts, a deep squat training robot based on the self-designed modular cable-driven unit is proposed, and a control system is designed to assist astronauts to achieve deep squat training. Firstly, the overall structure scheme of the robot is determined by the mechanism analysis of the human body deep squat. Secondly, a force servo control strategy is designed, including the establishments of the cable force planning part, the lateral force compensation part and the passive force controller of a single cable. Finally, the experiments of a single cable force control and man-machine deep squat training are carried out to validate the training effectiveness of the robot. The inhibition effect of the surplus force is more than 50% during the experiment of a single cable force control. The standard deviation of the system loading force is 7.52 N and the dynamic loading accuracy is more than 90.2% during the deep squat experiment under 200 N. The results indicate that the robot has a rational mechanism and occupies a small room with a stable control system and a high loading accuracy. It proves the robot can assist astronauts to conduct deep squat training during long-duration spaceflights.