The invention discloses an automatic dust removing device for a solar cell assembly. The dust removing device comprises a direct-current motor power supply switch, a direct-current motor, a ball screw, a linear guide rail and an electrostatic brush, wherein the electrostatic brush comprises an electrostatic generator and fan power supply switch, an electrostatic brush cover, a vent, an electrostatic generator, a fan, an electrostatic net, a dust absorption brush and a dust storage chamber; and the electrostatic brush moves up and down on the surface of the assembly during working and absorbs dust by using electrostatic effect, so that the purpose of removing the dust is fulfilled. The device has high automation degree and high work efficiency, saves a large amount of manpower and material resources, and can effectively remove the dust on the surface of the assembly so that the solar radiation intensity on the surface of the assembly is maximum and normal power output of the assembly is ensured; and through the device, hot spot effect in the assembly can be avoided, the assembly is protected, and the service life of the assembly is prolonged.