In order to use robot to replace manual work to complete the inspection of tunnel cable, a hanging rail inspection robot with PTZ lifting is designed and its walking process is analyzed. According to the requirements of the specific environment in the tunnel, the working principle and system composition of the robot are determined. The main structural modules of the robot are designed, and the sensing and control system of the robot is built. Based on the D'Alembert principle, the mechanical model of the walking process of the robot is established, and the driving force change law in the walking process is analyzed through simulation. The simulation results show that the walking speed of the robot is greater than 0. 8 m/s, the climbing ability is greater than 15 °, and the turning radius is less than 0. 5 m, so the robot has feasibility and practical value.