Abstract:The C18 unsaturated fatty acids in the seed oils of Euodia meliaefolia and E.fargesii were separated and identified by means of remote functional group modificationmethod and GC/MS. An usual linoleic acid, unusual 10-octadecenoic acid and a newconjugated acid as 9, 13, 15-octadecatrienoic acid were found. The composition of fattyacids in seed oils of E. meliaefolia and E. fargesii were palmitic 10.1%, 10.7%; stearic1.0%, 1.9%; palmitoleic 21.2%, 20.7%; 10-octadecenoic 28.5%, 31.7%; linoleic 24.2%,17.5% and 9, 13, 15-octadecatrienoic 15.0%, 14.9%, respectively.