The utility model provides a can rectify gas flow's oxygen rifle on line, belongs to converter equipment technical field for the gas flow of online rapid survey oxygen rifle. Its technical scheme is: the oxygen rifle in by lavalle shower nozzle, oxygen rifle outer tube, oxygen rifle pipe, oxygen rifle inner tube, air duct and mechanical type manometer constitute, has opened respectively on pipe, the oxygen rifle inner tube in oxygen rifle outer tube, oxygen rifle and has led air pipe hole, the one end of air duct is passed and is led air pipe hole and be linked together with oxygen rifle inner tube, the other end of air duct is connected with the mechanical type manometer of installing in oxygen rifle outside. The oxygen rifle is when site?operations, and the gas pressure of oxygen rifle inner tube can be measured and shown to the mechanical type manometer, through calculating the gas flow that can reach the oxygen rifle. The utility model discloses simple structure, convenient to use can calculate out gas flow according to the pressure gauge of oxygen rifle inner tube for flow to the flowmeter is proofreaied and correct, obviously falls the calibration cycle of low flow meter, guarantees the converter and normally produces.