Abstract: The determination of oxygen，nitrogen and hydrogen in V-5Cr-5Ti alloys by impulse heating inert gas fusion method and high frequency induction method was developed （oxyen by infrared determination and nitrogen, hydrogen by thermal conductivity）. The influences of releasing temperature, current, fluxing agent, crucible materical, blank value and sample mass on the determined result were emphatically discussed.The results show that oxygen and nitrogen in V-5Cr-5Ti alloys are determined with analytical power 5.0 kW, high temperature crucible and using nickel as flux, and the relative standard deviations（s_r） for oxyen and nitrogen are 8.8% and 12.4%(n=6), respectively, and the standard addition recoveries for oxygen and nitrogen are 93%-112% and 90%-110%, respectively. Hydrogen in V-5Cr-5Ti alloys are determined with analytical power 85%, quartz crucible and using nickel as flux, and the relative standard deviation （s_r） for hydrogen is 3%(n=6), and the standard addition recovery for hydrogen is 96%-104%.