Abstract: The Cyclina sinensis (Gmelin) is a important species formarinculture intensive exploitation of the StateTenth five-yearsplan due to their commercial value of fishery industry and their widely distributing of seashore in China. The paper preliminarydiscussed genetic diversity and genetic differentiation of wild Cyclina sinensis populations distributed in Zhuanghe Liaoningprovince (LZ) and Huidong Guangdong province (GH) areas, the physical geographic conditions including latirude、 climate andtemperature of habitat are much different between two populations of Cyclina sinensis, the annual temperature of the former area,for instant, is 12.6 centigrade lower than that of later, and the latitude of the former area is 16.98 higher than later. In the pre-sent study were investigated using the random amplified polymorphic DNA (RAPD) technique to detect the genetic variation andgenetic differentiation of two populations. A total of 22 ten-base primers were applied in the RAPD analysis, 179 and 181 frag-ments ranging from 210 to 2850 bp were amplified from the above two populations respectively. The primer yielded different pat-tern in terms of length and intensity of amplifications fragments. There were 24 species-special and 2 population-special bandswere amplified by the 22 primers from 40 individuals of two populations. After using the TFPGA (Tools For Population GeneticAnalyses) package designed by Mark P. Miller (1999) to figure out the proportions of polymorphic amplified fragments (P) andvalue of Average Heterozygosity (H)were 76.92%, 81.31%and 0.2815,0.3012 respectively. The genetic distance (D) and in-breeding index (Fst) between the twowild populations were 0.103 and 0.1997 respectively. The RAPD analysis revealed that thegenetic diversity was remarkably high for each group and the population differentiation of Cyclina sinensis was significant. Thege-netic differentiation of the populations and the seed introduction of this species were also discussed in this paper.