Pressure holding valve

A pressure maintaining valve. The utility model is comprised of a valve body (24), a valve core (25), a gas inlet component, a gas outlet component, a needle valve (10), a retaining mechanism and a spring pressure adjusting mechanism, a gas inlet cavity and a gas outlet cavity are arranged in the middle of the valve body (24), concentric perforated round holes (26) are arranged at the both ends of the cavity, a valve seat (8) is arranged in the middle, a section of cone hole is arranged on the valve seat, a valve core (25) is arranged in the hollow cavity, the sealing axles (1 and 12) at the both ends of the valve core are matched with the round holes (26) at the both ends of the hollow cavity, a cone body (9) which taper degree is smaller than the taper degree of the cone hole on the valve seat (8) is arranged in the middle of the valve core (25), the cone body (9) and the cone hole are matched at a contacting position (d) in a linear sealing way, and gas inlet and outlet parts connected with the hollow cavi