Abstract: To address the problem that the deformation error of the flexible cable of the flexible cable traction upper limb rehabilitation robot leads to the reduction of the robot's motion accuracy during the rehabilitation training process, an inverse modeling method based on the deformation intrinsic equation of the flexible cable error is proposed. Firstly, the mechanism of the rehabilitation robot is designed by combining the physiological structure and motion characteristics of the shoulder, elbow and wrist of the human upper limb, and the drive system adopts the parallel structure of flexible cable traction. The spatial equivalent model of the arm exoskeleton is established in MATLAB using the improved Denavit-Hartenberg (D-H) method relative to the human body. Secondly, based on the simultaneous consideration of the deformation of the flexible cable, the friction between the flexible cable and the pulley, and the position of the cable exit point, and combining with the force rotation method, the deformation error generated by the flexible cable in the actual traction direction is calculated inversely on the basis of the traction state of the flexible cable, so as to get the dynamic model of the cable traction system shape under the desired trajectory. The real-time dynamics model of the traction system is obtained by judging the state of the flexible cable, and the real-time tension of the flexible cable is obtained by combining the generalized inverse method. Finally, by simulating the deformation error of the flexible cable under the rehabilitation training trajectory, the change trend of the flexible cable is obtained and compared with the force and length of the flexible cable, which verifies the correctness of the inverse model of the flexible cable error, and provides the basis for the control and safety analysis of the flexible cable traction rehabilitation robot, as well as the ideas for the error analysis of the flexible cable traction parallel system.