The invention relates to the field of a water storage device about a water purifier, medical fire fighting, bathing, solar energy, a water pump, radiant floor heating, a boiler or a household appliance, and especially relates to a pressure water storage barrel, wherein the storage barrel comprises a pressure barrel body, and a reservoir bag and a water storage bag both which are arranged in the pressure barrel body, the top of the pressure barrel body and the bottom thereof are provided with a connecting nozzle, the water storage bag opening and the reservoir bag opening are respectively connected with upper and lower connecting nozzles, the connecting nozzle connected with the water storage bag opening is the water inlet and outlet, the connecting nozzle connected with the reservoir bag opening is the air inlet and outlet on which a valve core is arranged. When the device is disassembled for cleaning, the reservoir bag isn't affected, when the device is reassembled, air pressure cannot be again injected into the reservoir bag, thereby reducing operating processes, saving time and manpower and material resource, and greatly improving safety factor.