The invention discloses an electromagnetic valve. The electromagnetic valve comprises a main valve body, side cover plates and membranes and further comprises a first spring. The number of the side cover plates is two, and the side cover plates are oppositely arranged on the two sides of the main valve body. According to the technical scheme, after a two-level air compressor is in power failure, high-pressure gas and water of the two-level air compressor are smoothly discharged out of a system, and the problems of large current and high torque caused by repeated starting of the air compressorand corrosion caused by water staying in the device can be effectively prevented. Meanwhile, the situations that heat is dissipated after air compressor is in power failure, and even in the extreme weather, equipment cannot be frozen are achieved, normal work of the equipment is guaranteed, and the environment adaptation capability is improved.