A new type of crawler-type magnetic adsorption wall-climbing robot for derusting of ships was designed. The three-dimensional model of the robot, the adsorption device and the cleaning device, were established by SOLIDWORKS, and the static force model was established according to the actual working condition. Then, two kinds of common overturning risks of the wall-climbing robot were analyzed and the numerical simulation carried out by MATLAB software was used to obtain the minimum adsorption force. At last, the magnetic adsorption unit was simulated by ANSOFT MAXWELL, and the vector magnetic density is obtained, verifying the rationality of the design of the adsorption unit.