To study the germplasm resources and genetic diversity in the wild population of Orithyia sinica,the mitochondrial DNA 16S rRNA and COⅠ gene sequences were obtained from O.sinica wild populations by PCR amplification.A T base content of 16S rRNA and COⅠgene sequences were 67.7% and 61.4%,respectively,which were significantly higher than G C base content.From 515 bp of 16S rRNA gene sequences,4 haplotypes and 4 polymorphic sites were detected,and they were all singleton variable sites.As for 653 bp of COⅠ gene sequences,11 haplotypes and 23 polymorphic sites were detected,including 18 singleton variable sites and 5 parsimony informative sites.COⅠ gene sequences have more variations than 16S rRNA gene sequences,indicating that COⅠ gene sequences were suitable for analysis of genetic diversity of O.sinica.The results of genetic distances and phylogenetic analysis of 16S rRNA and COⅠ gene sequences were consistent with each other,showing that O.sinica have much closer relationship with crabs of Portunidae,and crabs of Grapsidae were together with that of Ocypodidae,which were consistent with classical taxonomy.Differentiation time of 11 species of crabs and vertebrates was deduced based on the genetic distance of 16S rRNA gene sequences,and the results showed that the radiation differentiation time of four families of crabs was between Paleocene and Eocene.This study is expected to provide important information for the protection and utilization of O.sinica resources of China.