Abstract: The present invention discloses a combined oxygen, nitrogen and hydrogen joint determination device and method based on thermal conductivity-infrared technique. In the device, a melting and extraction system comprises a carrier gas introduction pipeline, a chamber valve, an impulse furnace and a dust filter; an analytical gas transmission system comprises a flush valve, a bypass valve, a mass flowmeter and a first switching valve; a signal detection system comprises an infrared cell, an analysis purification reagent tube and a thermal conductivity cell; and a signal analysis system comprises a controller and a processor. The present invention realizes different joint determination modes by switching different gas paths, which can meet different determination requirements of different users.