Abstract: The transcriptome information of clam，Cyclina sinensis, was used to develop microsatellite markers in this study.After sequencing， 12 418 microsatellite loci were obtained， among them 8 422 mononucleotide repetitions accounted for 67.08% of the total， 1 501 trinucleotide repetitions accounted for 12.09%， and 1 419 dinucleotide repetitions accounted for 11.43%. The poly A/T type was the most frequent poly type accounting for 48.75% of the mononucleotide repetitions. Then， 81 pairs of primers selected randomly were designed for microsatellite loci verification and 27 polymorphic loci were obtained as result. Detection and assessment of polymorphism points were conducted in 30 clams and a total of 99 alleles were amplified. The number of alleles N_a at each locus was 2 to 6. The expected heterozygosity （H_e）， the observed heterozygosity （H_o） and the polymorphic information content （PIC） of each lucus ranked from 0.033 3 to 0.808 5， 0.000 0 to 0.678 6 and 0.032 3 to 0.764 5， respectively. Also， 19 loci deviated significantly from HardyWeinberg equilibrium （p<0.01）. The polymophic ESTSSRs developed in present study will be useful for molecular genetics study， quality evaluation and wildlife resource conservation for the clam C. sinensis．