17 half-sib families and 51 full-sib families of Hyriopsis cumingii were constructed by nested design. 40 individuals were randomly selected from each of these full-sib families when the individuals in the cages reached 1 cm, and the number was 2 040 in all. Shell length, shell height, shell width and body weight were measured of these individuals, and these data were used for genetic analysis. The heritability of these four traits was 0.356±0.047, 0.488±0.060, 0.453±0.055 and 0.518±0.050 respectively. The phenotype correlation and genetic correlation was between 0.476－0.709 and 0.574－0.868. There was enough genetic variance for selective breeding and when we have selective breeding program on weight, the other three traits would have some genetic improvement at the same time.