Four mating combinations of Hyriopsis cumingii inclouding white♂×white♀(WW), white♂×purple♀(WP), purple♂×white♀(PW) and purple♂×purple♀(PP) were established by diallel crossing of white and purple selected strains, and then the number of offspring whose nacre color separation occurs was count and analysed by Chi-square test. The results showed that the nacre color of white inbred offspring was all white, no occurrence of color separation; In hybrid offspring, the color separation appeared two kind of situations. The offspring of one situation were all purple nacre color, and the other entirely different one were color separation occurrence, with the segregation of purple and white individual fits a ratio of 1:1; In purple inbred offspring, the color separation appeared two kind of situations too. The offspring of one situation were all purple nacre color, and the other entirely different one were color separation occurrence, with the ratio of purple and white segregating individual was 3:1. It indicated that shell nacre color of H. cumingii which can be inherited stably was controlled by genes, and it belong to qualitative trait. The purple nacre color trait was dominant over white nacre color, and the two kinds of color traits there were no maternal inheritance. The white individual was recessive homozygote, which purified breeding was more easily, while the purple individual may be homogeneous or heterogeneous, so purified breeding was relatively difficult.