The invention relates to a wall-cleaning robot based on the positive and negative pressure absorption principle. The wall-cleaning robot of the invention solves the problems of complicated structure,bad wall absorption effect, and bad obstacle-crossing capacity and so on, existing in the existing wall-cleaning robot. A cleaning mechanism (71) and a water inlet and outlet mechanism of the invention are installed in a shell body (2); a wheel type traveling system (70) is installed at the lower part of the shell body (2); a three-phase motor (13) is installed on the upper end face of the shell body (2); the outer rotors of the three-phase motor (13) are respectively and fixedly provided with a propeller (1) and a centrifugal fan in sequence from top to bottom; the external housing of the three-phase motor (13) is communicated with the inner cavity of the shell body (2); a dry brush (9), a wet brush (27), a suction roll (32) and a squeeze roll (44) are installed in the shell body in sequence from front to rear. The wall-cleaning robot of the invention has the advantages of good wall absorption effect, better obstacle-crossing capacity and simple structure and can be remotely controlled.