A novel mechanism for 110 kV power transmission line inspection robot is presented according to the requirements of inspection tasks and characteristics of obstacles on power lines. Its configuration is introduced，and the navigation process of typical obstacles is planned. Then, the kinematics equations and the workspace are established. Furthermore, the simulation of the navigation of the strain clamp and test of navigation the jumper in the laboratory have been carried out. The simulation results demonstrate that the mechanism has such characteristics as compact construction, good motion stability and excellent obstacle negotiation capability.