In the gear driving system with large reduction ratio, the existence of backlash will lead to the weak dynamic performance of the servo system. Aiming at the common analysis method of the backlash with mathematical modeling and simulation, the solid model in the Creo is established and then imported into Adams to run the co-simulation with the MATLAB/Simulink. On this basis, the effectiveness of the dual-motor driving anti-backlash strategy is verified. The extended state observer (ESO) based on the dual-motor model is used to compensate the influence of disturbance. The results show that the dual-motor driving anti-backlash method can solve the problems of the backlash in the gear driving mechanism, and the ESO can suppress the disturbance torque effectively.