The shell color characters of natural population Cyclina sinensis (Gmelin) were observed and analyzed. The natural group was divided into white and purple shell groups for artificial breeding respectively. The F₁ shell color segregation was counted and analyzed. The influence of different sediments on F₁ shell color expression was analyzed by experiment with mud, silt and fine sand. Results showed that, (1) F₁ displayed 4 shell color types, the percentage difference of same shell color individuals between the two groups was significant (P<0.01), the F₁ shell color purified the color of parents, which indicated white and purple shell color are truly hereditary; (2) the purple shell color depth was obviously influenced by sediment, and muddy sediment made the purple shell color light and lowered the individual percentage; sandy sediment was conducive to the purple shell color expression, and percentage difference between fine sandy and muddy reached significant level (P<0.05), but the sediment influence did not exceed 1/4 of the genetic capacity; (3) the purple shell percentage of purple group F₁ was more than 70%, nearly 4 times of not separated parents(18.71%), so that purple shell individuals have been significantly purified. This creates good conditions for breeding pure purple shell strain or polygenetic strain.