The genetic diversity of seven wild Scylla paramamosain populations,collected from Hangzhou Bay(HZ),Sanmen Bay(SM),Minjiang Estuary(MJ),Dongshan Bay(DS),Zhujiang Estuary(GD),Beibu Bay(GX),Qinglan Estuary(HN)in China were investigated using seventeen microsatellite markers.The number of alleles(A),number of effective alleles(N_e),polymorphism information content(PIC)and heterozygosity(H)were all determined.The Hardy-Weinberg Equilibrium was checked by χ² Test.The genetic distance was computed based on the allele frequency.A dendrogram was built on the unweighted pairgroup method with arithmetic means(UPGMA)results using PHYLIP software package(Ver 3.5).F-statistics analysis and the degree of population differentiation between the seven wild populations using analysis of molecular variance model (AMOVA) were computed by ARLEQUIN(Ver 3.1).A total of 253 alleles were obtained at the seventeen microsatellite markers in seven populations.Polymorphic information content (PIC) value per locus was greater than 0.5,indicating the seventeen loci were highly polymorphic.The mean number of alleles and effective alleles ranged from 9.41 to 10.94,5.42 to 6.87 respectively.The heterozygosity (H) ranged from 0.511 to 0.563.The data suggested that all the seven wild populations of Scylla paramamosain had little high genetic diversities.Analysis of molecular variance (AMOVA) revealed that the variation within populations was 94.13%,whereas the variation among populations explained 5.87% of the total variation.F-statistics analysis detected significant genetic differentiation among the seven wild populations,with the F_ST value ranged from 0.035 5 to 0.081 7.Genetic differentiation among populations was statistically significant.88.24% of the population loci showed significant deviation from the Hardy-Weinberg equilibrium.There was heterozygote deficiency at all loci.The genetic distances among populations ranged from 0.253 0 to 0.571 9.Cluster analysis indicated that HZ and SM populations,joining together for the closest relationship,were clustered with MJ and DS as one cluster.GD and HN populations were clustered together,while GX was an independent cluster.