Forty-four SSR primer pairs were used to amplify genomic DNA of 21 peanut genotypes in genus Arachis.Thirty-four of the 44 primers were detected which displayed polymorphism among 21 peanut genotypes and amplified 190 loci alleles in total.The average number of alleles per locus was 5.59 with range of 3 to 11.The genetic diversity level among 21 genotypes in genus Arachis were very high and genetic distance(GD) was from 0.08 to 0.95 with an average of 0.63.The results from UPGMA analysis indicated that genetic differentiation among the genotypes from different sections was bigger than that from the same section.Genetic diversities of species in section Procumbentes was richer than that in other sections.There was also considerable polymorphism among the different genotypes of one same species.The genetic distance between cultivated peanut and several species including A.duranensis,A.villosa and A.batizocoi belonging to section Arachis was relatively more close in the comparison with some other species which was in accordance with peanut classification system.