To study the volatile oil of Korean Epimedium Nakai,it is extracted by accelerated solvent extraction(ASE),and then identified by gas chromatography-mass spectrometry(GC/MS).In the completely random-ized design optimization of extraction conditions ASE,the extraction yield of volatile oil is 4.0%,by retrieving NIST 98 spectrum library,91 of them were confirmed.With peak area normalization method,the chemical in-gredients in the relative content of volatile oil were obtained.The result is that the main constituents of Korean Epimedium volatile oil are:4,4a,5,6,7,8-2(3H)-naphthalene-one;1,2-benzene dicarboxylic acid;10hydrogen-4a-methyl-1-naphthalene;N,N’-2(1-methyl)-1,4-phenylenediamine;-butyl-1,2-phenyl bicy-clic 2-carboxylic acid;two decanoic acid ethyl ester.