Abstract: The invention relates to a pressure maintaining gas cylinder valve. It consists of a pressure retaining device: The axis of the pressure retaining device and that of the valve element are in the same vertical plane; the pressure retaining device has a mounting base, a spring and a valve are located in the mounting base: the valve is in the valve element near the air outlet; the front section of the valve is near the air outlet, while the rear section of the valve is in the mounting base; the spring is between the valve and the mounting base. Because the invention has no eccentricity, the gas channel is smoother and the volume of the cylinder valve is greatly reduced. The mounting seat of the pressure retaining device not only provides support for the valve and spring, but also ensures that the stroke of the valve element is not interfered.