A solenoid valve includes a plunger, an actuating device, and an air tap assembly. The plunger is connected to the actuating device. The air tap assembly is secured to the actuating device and has a cavity. The air tap assembly includes a main body, and first and second tubes. The first tube protrudes from the main body and defines a first through hole. The main body defines a second through hole communicated with the first through hole and the cavity. The second tube defines a third through hole. The main body defines a fourth through hole extended from the third through hole and a fifth through hole extended from the fourth through hole to the cavity. The fifth and second through holes are parallel. The plunger head is used to seal the second and fifth through holes.