Abstract: Taking the F₂ generation of Haliotis diversicolor aquatili descended from the hybridization between Chinese cultured population and Japanese wild population as the base population, we carried out a selective breeding experiment by mass selection to investigate the selective responses and to estimate the realized heritability.We selected 10% individuals of the largest shell length as parents for the selected groups (SS), then randomly selected the other 10% individuals from the base population as parents for the control groups (SC), and the mass selection experiment has a selective intensity of 1.755.Results reveal that no significant difference was found in egg size and fertilization rate (P>0.05), while the selected groups show growth advantages in various degrees compared to the control groups in the larval settlement rate, larval metamorphosis rate, larval survival rate and postlarval growth (P < 0.05).The survival rate of 50-dph juvenile abalone in selected groups reached 35.07%, significantly greater than that in control group which was 23.62% (P < 0.05).The ranges of the selective responses and realized heritability of 40~270-dph individuals in selected groups were 13.64%~81.88% (31.63% on average) and 0.21~0.53 (0.36 on average), respectively.The average shell length in selected groups was significantly greater than that in control groups (P < 0.01).Therefore, the experiment indicates that the mass selection is effective for the genetic improvement for cultured H.diversicolor aquatili populations.