Abstract: In order to better study the fatty acid composition in Mucor-type Douchi, it was esterified with acid, alkaline and acid-alkali combination method.The esterified products were analyzed by gas chromatography-mass spectrometry ( GC-MS) .On the basis of this, the influencing factors were discussed, including the extraction time, the esterification temperature and the time of methyl esterification. The difference of fatty acid composition was analyzed by the three methods, and the best method of methyl esterification was obtained.The results showed that 12 kinds of fatty acids could be determined by the method of acidalkali combination method in three methods. The best conditions for the pre-treatment process was that oil extraction time of20 min, methyl esterification temperature of 60 ℃, esterification time of 30 min when Linoleic acid was used as the evaluation index, and the linoleic acid content was 54.22%. The results showed that under certain conditions, the fatty acid composition and content of Mucor-type Douchi were analyzed compirehensively by the acid-alkali combination method.