Genetic diversity of 4 wild populations(Laizhou,Haizhou,Dalian,Qingdao)of Charybdis japonica was assessed by 10 microsatellite markers.Results showed that the number of averages allele of 10 loci was 13.600 0 and alleles obtained from different primers ranged from 11 to 17,the number of average effective alleles was 8.592 0;Observed heterozygosity value(H_o)was 0.318 2 to 0.858 4 and expected heterozygosity value(H_e)was 0.846 6 to 0.923 9;Average polymorphism information contents was 0.828 0 to 0.914 0,explained high level of genetic diversity in 4 wild stocks.Coefficient of gene differentiation F_ST ranged from 0.032 74 to 0.088 03,each group had larger genetic differentiation.Genetic identity(I),genetic distance (D) and cluster dengrogram between 4 stocks of C.japonica showed that Qingdao Bay was closest relative with Haizhou Bay stock,but Haizhou Bay was farthest relative with Laizhou Bay stock.