Catering to the new strategic project of smart grid, this paper introduces a design of high-voltage transmission inspection robot, which worked on earth wire and so that automatically inspection on the entire transmission line becomes the reality. Robot control system using hierarchical control structure, included remote management host, robot control ontology and motor drives. Under the auto-operation mode, it makes its own decisions for planning the sequence of operations according to knowledge data base without the upper layer's involvement. Using image recognition obstacle and expert data base, the combined method of using laser sensor over obstacles, the inspection robot autonomous obstacle had came true. The experiment and test results show that the inspection robot system has possessed the capabilities of navigation and inspection tasks on the power lines. It has a good application prospect.