In order to figure out phylogenetic relationship and genetic diversity of different geographical populations,genetic analyses of Aedes albopictus were performed based on mitochondrial gene COI.Based on samples collected from most distribution regions in China,mitochondrial gene Cytochrome C Oxidase Subunit I was obtained through PCR and DNA sequence.Together with some COI sequences downloaded from GenBank,60 COI sequences with the final length of 598 bp were used for subsequent analyses.Results showed that there was no obvious divergence according to phylogenetic analyse,all sequences were clustered together in Maximum Likelihood tree.Sixteen haplotypes were detected,and four of them shared haplotypes.Haplotype diversity (Hd) was 0.737,nucleotide diversity (π) was 0.20 ％.Population genetic differentiation analyses demon strated that Hainan population showed obvious divergences.In the network of haplotypes,H1 and H6 was found to be the primary haplotypes,and they formed two radical centers.All these results indicate that A.albopictus populations of China are expanding presently,and Hainan population become differential with other geographical populations,which probably attribute to geographical isolations.