Abstract: Fatty acid compositions in the products of transmethylesterification of plant phosphatidylgly cerol catalyzed by H 2SO 4、BF 3 and KOH under different reaction conditions were measured and the relative methy lesterification yields (REY) of individual acyl fatty acids were given.In the fatty acid compositions there was no significant change when catalyzed by acid.On the contrary,with the increase of temperature or time the relative content of trans 3 hexadecenoic acid (16∶1(3t))in the products and the REY of all acyl fatty acids decreased when catalyzed by alkali.The decrease of both relative content and REY of 16∶1(3t) was the most notable phenomenon which showed that the 16∶1(3t) was more liable to decompose than other fatty acids when catalyzed by alkali.