solenoid valve for air consists of electrical part and pneumatic part. When the electrical part of the solenoid valve is charged, the electromagnetic force produced by the solenoid coil lifts the closing part from the sealed air hole, compressed air enters the pilot valve, and the pilot valve works; when the power is cut off, the electromagnetic force disappears, while the valve operates in the opposite direction. The pneumatic actuator of the solenoid valve moves in the joint action of the piston of the pilot valve and the spring at the other end of the main piston rod to complete the switching of the two five-way connections.