Gate valve with automatic pressure relief structure

The utility model discloses a gate valve with an automatic pressure relief structure. The gate valve comprises a valve body and a pressure relief unit, the pressure relief unit comprises a round hole, a cylinder, a cylinder, an annular groove, a square groove and an exhaust port, the round hole is formed in the middle of the right side of the valve body, the inner side face of the round hole is fixedly connected with the left end side face of the cylinder, the inner left end of the cylinder communicates with the interior of the valve body, and the cylinder is slidably connected to the inner left end of the cylinder; an annular groove is formed in the middle of the cylinder, at least eight square grooves are evenly formed in the circumferential side face of the left end of the cylinder in the left-right direction, the right ends of the square grooves communicate with the interior of the annular groove, the exhaust port is formed in the middle of the upper side of the cylinder, and the cylinder slides in the cy