The present invention provides an improved pressure relief valve comprising a tubular main body with a pressure relief peroration, a pressure adjustor with an anti-leakage rubber and an anti-reverse unit; wherein the main body comprises a mount opening, an air outlet and a conduit between the air intake and outlet. The conduit comprises an abutting portion; the pressure adjustor is mounted on the air intake and the anti-reverse unit is fastened onto said outlet. As the pressure adjustor is connected to an air pump and said outlet is connected to an air-filling article, the pressure value of said article is set via the pressure adjustor. As said article reaches said pressure value, the anti-leakage rubber of the pressure adjustor is pushed such that air is released from the relief perforation and the anti-reverse unit abuts the staged portion of the conduit to maintain the article at a stabilized filling state.