The invention relates to agricultural cultivation facilities, in particular to an automatic snow removing device for a greenhouse, which comprises a snow blower, and is characterized in that the snow blower comprises a space cam, the space cam comprises a wheel core and wheel hubs which are concentric and alternate with the wheel core, the wheel core is cylindrical, a circle of smooth wheel groove with two ends connected is formed in the circumferential circular surface, and the wheel hubs are connected with the wheel core. The two wheel grooves are close to the front end of the wheel core, the two wheel grooves are close to the rear end of the wheel core, and the positions, close to the front end, of the wheel grooves and the positions, close to the rear end, of the wheel grooves are distributed in a cross shape. Compared with the prior art, the snow blower is unique in structure, the snow blower nozzle not only can pitch up and down, but also can swing left and right, accumulated snow can be thoroughly removed, and the automation degree is high.