The invention relates to a device for automatically cleaning glass of a glass window, belonging to the field of energy saving and environmental protection of household equipment. The device comprisesa frame, a first support, a first pipe hole, a hose, a first screw nut, a first coupling, a first stepping motor, a second bearing, a sewage outlet, a third support, a second stepping motor, a secondcoupling, a first lead screw, a second lead screw, a glass, a second lead screw nut, a fourth support, an inner cleaning component, a flashing plate, a weight, a water pump, a water absorbing ball, anouter cleaning component, a water inlet, a second tube hole, a battery, a control panel and a solar panel. The device can solve the automatic cleaning work for window glass, and the automatic cleaning of window glass can be carried out by collecting rainwater and adding water by oneself. Dual-stepping motor is adopt to drive that movement structure of the double screw to drive the up and down movement of the inner clean assembly, so that the inner cleaning assembly can move up and down steadily, and the stability of the movement is improved, so that the clean work of the device to the glass is cleaner and more thorough.