Abstract: The radioactive noble gas ³⁷ Ar which is characteristic activation product of underground nuclear explosion, can be used for Comprehensive Nuclear-Test-Ban Treaty Organization on-site inspection to verdict whether a suspicious nuclear explosion is happened. Based on the principle of pressure swing adsorption and preparative chromatogram separation, argon separation and purification method of air sample is established by using LiX zeolite and 4A molecular sieve. The recovery rate of argon is greater than 65%, and the argon purity meet the requirements of radioactivity measurement. Two hour processing time is adequate for on-site inspection.