The invention relates to a walking system for a tunnel inspection robot, and belongs to the technical field of tunnel disease detection. The walking system comprises haunch tracks and a vault track, wherein the haunch tracks are all located on the side wall of the tunnel, the vault track is located at the top end of the tunnel, chain transmissions are arranged between the vault track and the haunch tracks, both ends of the haunch tracks and the vault track are provided with contact sensors, the haunch tracks and the vault track are used for the inspection robot to move and comprise variable tracks and fixed tracks, the variable tracks are connected with track change cylinders, and the inspection robot comprises an image acquisition system, a robot control system, a wireless communication system and a mobile inspection system. The walking system, by arranging tracks on the haunch and the vault, can cover the disease detection of all parts of the tunnel lining, and realizes the track change control of the inspection robot in different tracks through the track changing electric cylinders and the chain transmissions.