Abstract: Ten marine microalgae were examined for their fatty acid compositions of the total、 neutral and polar lipids.Lipids of marine microalgae were extracted by the method of Bligh and Dyer.Total lipid content was determined by gravimetry after lipid extract exapo-ration under reduced pressure.Methyl esters of fatty acid (FAME) were obtained by the method of Carreau and Dubacq and purified with thin-layer chromatography.Then, FAME was performed on a GC 1102 instrument, made in Shanghai, supplied with an electronic integrator.The lipid contents of 10 marine microalgae were more than 15% .The polar lipids usually served as the main lipid and provided mostly polyunsaturated fatty acids.The neutral lipids, containing more short chain fatty acids, were the main deposited lipids.Large amounts of 16:4(n-3) and 18:3(n- 3) might be used as the chemotaxonomic marker of Chlorophyceae.A significant amount of 20: 5 ( n-3 ) in Chlorella and Nannochloris, distinguished Eustimatophyceae from Chlorophyceae.The Prasinophyceae and Chlorophyceae had closely related fatty acid compositions.The major fatty acids of Chloromonadophyceae were 16:0 、1:4(n-3) and 20:5(n-3).The fatty acid compositions can afford the taxonomic classication of marine microalgae, and give the information of polyunsaturated fatty acids produced by marine microalgae.