Reishia clavigera (Mollusca: Muricidae) is a common species in the rocky intertidal zone along the coastal islands of Wenzhou, Zhejiang Province in China. There are many islands and their hydrological environments are complex in coastal region of Wenzhou. In order to investigate the genetic diversity and population structure of R. clavigera, we collected 158 individuals from 14 populations (Table 1 and Fig. 1). We amplified 672 bp length of mitochondrial cytochrome c oxidase submitⅠ(COⅠ) gene (primer LCOⅠ 1490 5′-GGT CAA CAA ATC ATA AAG ATA TTG G-3′and HCOI2198 5′-TAA ACT TCA GGG TGA CCA AAA AAT CA-3′), which could provide the basic data on their resources and genetic utilization. The ratios of A, T, C, G were 23.0%, 38.4%, 17.4% and 21.2% (Table 2)，respectively, which was in accordance with the mitochondrial composition. All sequences obtained included 108 polymorphism sites (57 parsim-information sites and 51 singleton sites) (Table 2). The nucleotide diversity was 0.008 0, while haplotypes diversity and the average number of nucleotide differences were 0.978 and 5.328, respectively (Table 2). A total of 102 haplotypes were detected (Table 3). The genetic distance between populations ranged from 0.005 7 to 0.011 1, and the genetic distance within the population ranged from 0.005 7 to 0.010 8 (Table 4). The genetic distance between groups from Niyu Island and Dazhushi Island was minimal, and the genetic distance within groups from Dongtou Island was maximal. The correlation between genetic distance and geographical distance based on COⅠ gene fragments was significant (R2 = 0.134, P < 0.01), but there was no geographical isolation (r = 0.365, P = 0.11) (Fig. 2). The topological structure of R. clavigera in ML analysis had no obvious geographical structure (Fig. 3 and Fig. 4).