The invention discloses a pressure regulating valve. The body of the pressure regulating valve is provided with an air inlet and an air outlet. A valve cap is arranged under the body and the valve capis provided with a pressure regulating choke plug. A pressure regulating seat is arranged on the upper surface of the body. The top end of the pressure regulating seat is a pressure regulating button. An elastic membrane body is arranged between the pressure regulating seat and the body. The central of the elastic membrane body is provided with a mebrane seat. The upper end of the mebrane is fixed with a mebrane and the lower end is provided with a guiding shaft. The central of the mebrane is a sealing cavity. The upper part of the sealing cavity is provided with a sealing plug with an air discharge hole. The upper part of the body is provided with a guiding cavity. The guiding shaft on the mabrane seat and the guiding cavity on the body form a moving pair. The invention effectively solves the problems exited in the current pressure regulating valve that the center of the mabrane is easy to deviate and the air flow is not stable enough. The invention has the advantages of reasonable design, stable air flow, good pressure regulating effect and long service life. The quality of the pressure regulating valve has been improved remarkably.