The Pacific oyster , naturally distributed in the Pacific Coast of Asia, has become a global aquaculture species owing to its high fecundity and strong environmental adaptability. It is also the most highly produced mollusk species worldwide, and China is the top oyster-producing country. Although China is the highest producer of oysters with a long history of oyster aquaculture, there are no well-documented cases of selective breeding. To genetically improve the productivity traits of , we initiated a selective breeding program in 2007, concentrating on the establishment of selected strains by mass selection with fast growth rate. After eight generations of selection, significant genetic gains in growth rate were observed in the selected strains. In 2014, the fast-growing strain of ‘Haida No.1’ was established. However, the genetic parameters of growth-related traits in Haida No.1 are still undetermined. As a result of successive selection in closed population, genetic parameters varied between different generations of selected strains. The estimates of heritability and genetic correlation for growth-related traits in Haida No.1, which experienced numerous generations of selection, is of great benefit to long-term breeding program, contributing to the evaluation of increased genetic gains in future generations. In the present study, genetic parameters were estimated for growth-related traits in Haida No.1 after eight and nine generations of selection. A total of 41 and 28 full-sib families were obtained by a nested mating design (1 sires×3 dams) consisting of 60 and 40 broodstocks, which were obtained from the eighth-and ninth-generation selected strains of Haida No.1 in 2015 and 2016, respectively. The shell height, shell length, shell width, and body weight of 2,070 progeny representing 69 full-sib families were recorded at the age of 330 d. The variance components and genetic parameters were obtained from multi-trait animal models using ASReml 3.0 in the R Programming Language. The growth-related traits of Haida No. 1 had a high value of coefficient of variation, which showed a potential for successive selective breeding. The phenotypic correlations between the growth-related traits were positive and varied among different traits. The genetic correlation between body weight and shell shape-related traits (shell height, width, and length) was positive, ranging from 0.40 to 0.66. The heritability estimates of shell height, shell length, and body weight ranged from 0.16 to 0.37, belonging to moderate and high levels of heritability. These results suggest that the effects of successive mass selection on the genetic parameters of growth-related traits in Haida No. 1 were negligible. The high genetic diversity and stable genetic structure of selected strains of Haida No. 1 might be responsible for the high estimates of growth-related trait heritability. The results provide important information for future breeding programs of ‘Haida No. 1’.