The swimming crab is widely distributed in the coastal waters of China,Japan and Korea.This species is one of the most common edible marine crab in the East Asia.To assess the fatty acid composition and variation of swimming crab populations and to develop a genetic resources identification technique based on fatty acids biomarkers,a multivariate analysis method was used to study fatty acid composition difference of swimming crab P.trituberculatus along China coast,the six geographical populations from China Sea(Dalian,Dongying,Lianyungang,Zhangzhou,Zhoushan and Zhanjiang)in autum and winter.A set of fatty acids as fingerprint technique was developed for identifying different populations.The crabs from the six population all contained 27 kinds of fatty acids among which the total volume of five kinds of fatty acids C18∶1n9t,C16∶0,C22∶1n9,DHA and EPA was over 82%,and multivariate ANOVA revealed that there were significant differences among the six populations(P<0.01).As fatty acid fingerprint markers,the five kinds of fatty acids C18∶1n9c,C20∶1,C22∶1n9,ARA and EPA,were effective to identify the six-populations of crabs for the total discriminant accuracy amounted to 88.46%.The results of cluster analysis indicated that there were no significant correlations between geographical distance and Euclidean distance based on 27 kinds of fatty acids.The reason of population differences of fatty acids was probably related with feed composition in habitat of the swimming crabs.