Decompression air supply valve for toilet

The invention relates to the field of ship living utensils, and provides a decompression air supply valve for a toilet. The decompression air supply valve comprises a hand wheel, a screw rod, a spring seat, a main spring, an exhaust seat, a valve body, a main valve disc and a return spring; the upper part of the screw rod is connected with the hand wheel; the lower part of the screw rod penetrates through an upper cover to be connected with the spring seat; a thread kinematic pair is arranged between the screw rod and the upper cover; the upper cover is sleeved with the upper part of the valve body; a bottom cover is arranged at the bottom of the valve body; the upper part of the main valve disc is connected with the exhaust seat; the return spring is arranged between the lower part of the main valve disc and the bottom cover; the main spring is arranged between the spring seat and the exhaust seat. The pre-pressing force of the main spring is adjusted by rotating the hand wheel to drive the screw rod to move