A robot includes a truss assembly, a walking assembly, a power unit, and a rack including a guide pillar, a second link. The truss assembly is disposed on the top of the rack. The walking assembly is disposed in the rack and fixedly connected to the rack through a bearing. The power unit is disposed on the rear end of the rack. An oil tank is provided with a hole. The truss assembly is configured to place the robot into the oil tank through the hole. The walking assembly is configured to drive the robot to move along the axis of the oil tank and to prevent the robot from toppling in the oil tank. The power unit is configured to clean the inside of the oil tank. The walking assembly includes two active walking assemblies, a drive assembly, and a folding assembly.