With the method of PCR,the Cytochrome oxidase subunit I(COI) gene is amplified to investigate the genetic diversity and genentic difference of three populations of Macrobrachium rosenbergii,including F_1 of wild population from Burma,breeding population from Guangxi local farm and cultured population from Jiangsu Province,10 endonucleases(ApaI,Acc65I,Fnu4hI,BsrfI,BsrI,KpnI,HphI,FokI,BanI,TaqI) are applied to digest the PCR products of COI gene from 30 samples,10 samples per population.The digested DNA fragments are shown with 3% agrose gel.The electrophoresis patterns indicate that in COI gene,these three populations have 2 polymorphic loci,11 kinds of endonucelease patterns and 3 kinds of genotypes.The proportion of polymorphic loci,mean heterozygosity,genotype diversity respectively are:22.2%,0.055 6 and 0.047 2 in F_1 of wild population;22.2%,(0.040 0) and 0.039 8 in breeding population;11.1%,0.010 6 and 0.008 3 in cultured population,which shows that F_1 of wild population and breeding population have higher genetic diversity than cultured population,while genetic difference among these three populations is not significant by t-test(P>0.10).The UPGMA clustering phenogram indicates that the breeding population from Guangxi has a closer relationship with cultured population from Jiangsu than that with F_1 of wild population from Burma,and to some degree reveals the effectiveness and limitation of artificial breeding in Macrobrachium rosenbergii.