The invention provides a non-contact type magnetic adsorption wall-climbing robot adaptive to complex wall surface operations. The wall-climbing robot comprises a vehicle body, an adsorption device, moving modules, a mechanical arm, a nondestructive inspection module, a polishing and welding module, a paint spraying module and a control sensing module. In the operation process of the wall-climbing robot, crawler belts of the moving modules can be attached to the inner wall of a steel pipe in a self-adaptive mode; and meanwhile, a frame of the vehicle body is provided with the moving modules, the adsorption device, the mechanical arm and the control sensing module, and hence the nondestructive inspection module, the polishing and welding module and the paint spraying module can be replaced according to different functions of the wall-climbing operation of the robot. The non-contact type magnetic adsorption wall-climbing robot has the characteristics that modular design is adopted, various detection and maintenance operations can be executed, loads are large, and no power source is required in the adsorption device; and the functions of pressure steel pipe wall climbing, welded joint nondestructive inspection, welded joint repair and welded joint surface coating corrosion resistance can be provided.