Abstract: Because of the reasons that hydrazine is flammable and explosive, slowly reacts with oxygen, toxic, etc., it is substituted by acetone oxime as deoxidant in Yinjin Branch of Chongqing Natural Gas Purification Plant General. Analysis results show that the acetone oxime has better deoxidization effect and lower toxicity than hydrazine, and it does not affect the water vapor system, so that it can protect the equipment and has inhibit effect. Further more, acetone oxime can also reduce the production cost, therefore, it is more economical and practical.