Pressure measuring instrument

A pressure measuring instrument for a pressure vessel comprising a pressure-measuring hole, a hole wall of the pressure-measuring hole being provided with a first screw connection section and a second screw connection section, and the first screw connection section being farther away from an opening of the pressure-measuring hole than the second screw connection section, wherein the pressure measuring instrument comprises a gauge body, a connecting component and a pushing component, the connecting component comprises a first connecting member and a positioning sleeve which are connected with each other to form a corotating relationship, and the first connecting member comprises a first external thread section and a second external thread section connected to each other, and the first external thread section is used for a pressure-measuring hole threaded with a pressure vessel, the second external thread section protrudes from the pressure-measuring hole, the positioning sleeve is rotatably screwed to the second external thread section, and the positioning sleeve is configured to provide a force to the pressure vessel, and the pushing component is configured to pass through the connecting component and be pushed by a fluid in the pressure-measuring hole to push against a pressurize unit of the gauge body.