A facade cleaning machine comprises a rack (1), four symmetric mobile pulleys (11) which have electric motors and are fixed on the inner surface of the upper end of the rack, as well as four symmetric fixed wheels (12) which are fixed on the inner surface of the lower end of the rack, wherein three suction disk fixation rods (24) connected to suction disks are fixed on the left and right sides of the rack (1) respectively; a brush set frame (3) is fixed between the movable pulleys (11) and the fixed wheels (12); two cable fixation ends (4) are fixed on symmetric parts on the rack (1), the rack is connected to a lifting device (42) with an electric motor by a fixed-length cable (41), and a lifting cable (43) is connected to a lifting device (42); and a control module (5) is connected to the motors on the movable pulleys (11), a vacuum pump (22), the motor on the lifting device (42) and a pump conveying device on a detergent box (34). Through use of the device, a building outer facade can be cleaned automatically, and consumption of manpower can be reduced.