Abstract: A wire-driven cosmonaut-enginery-training robot based on the flexible Stewart platform is presented to prevent muscle strength decline,skeletal muscle atrophy and impairment of muscle function of cosmonauts who live in the micro-gravity environment for a long time.Based on force analysis on the robot system,a quasi-closed-loop virtual-gravity control strategy is proposed based on single-wire-tension closed loop control.Finally,the simulated experiment about virtual-gravity control is made on the experimental prototype.The results show that the control strategy is feasible and can realize virtual-gravity loading control in the process of human motion.This research lays a theoretical basis for realizing virtual-gravity loading control by wire-driven robots in the microgravity environment.