| In order to create a new strain with deep cupped shell shape of Crassostrea hongkongensis and better growth traits, a breeding program of truncation selection was initiated based on the 2-year-old culture population of wild Crassostrea hongkongensis collected naturally from Taishan Town Bay, Guangdong Province. The index of shell depth was used as an indicator, with 10% retention rate and 1.755 selection strength. The genetic parameters including selection reaction, genetic gain and realized heritability in larval stage, intermediate cultivation stage and later grow-out stage were estimated. The results showed that the shell height and index of shell depth in selected group were higher than that in control group, and the genetic parameters increased with the growth of individuals, showing a favorable genetic improvement potential. The average selective reaction, genetic gain and realized heritability of shell height at larval stage is 0.363±0.167, (1.678±0.416)% and 0.207±0.095, respectively; at intermediate cultivation stage is 0.639±0.115, (7.618±2.666)%, and 0.364±0.065, respectively; and later grow-out stage is 0.668±0.179, (8.861±3.072)% and 0.381±0.102, respectively. At the later grow-out stage, the average selective reaction, genetic gain and realized heritability of index of shell depth is 0.748±0.066, (9.090±0.565)%, and 0.426±0.038, respectively. The research provided a useful data for the creation of a new strain with deep cupped shell shape and good growth traits in Crassostrea hongkongensis .