A crawler-type wall-climbing underwater trash-cleaning robot is characterized by comprising a driving module, a transmission module, a millstone module, a lifting module and a frame module, a wall-climbing robot adopts a bilaterally symmetrical and front-back asymmetrical structure, and adopts a transmission mode of rear wheel driving and front wheel driven, so that the gravity center of the wall-climbing robot can be moved downwards structurally, and the adsorption stability of the robot can be improved; a chain is selected for transmission, torque and power are transmitted through meshing ofgear teeth of a chain wheel and chain links, and a transmission device is mainly composed of a chain, a driving chain wheel and a driven chain wheel. The chain transmission has very obvious advantages that the machining and assembling precision is not high, the transmission is very stable in the transmission process, and the slipping phenomenon is avoided; the robot has multiple functions of adsorption, wall climbing and dirt removal, and is high in practicability and maneuverability, compact in structure, convenient and easy to operate and control and high in durability.