Abstract: To study the growth traits genetic variation in open-pollinated families of Pinus massoniana, we used the genetic testing forest established by the open-pollinated offspring of 14 superior plants as the research material, and the tree height, diameter at breast height and individual volume of 1 year, 3 years, 6 years, 8 years and 10 years as evaluation indicators, the genetic variation pattern of the family were investigated and then the suitable age for early selection was estimated, the superior families and superior individual plants were selected based on 10 years volume. The results showed there were extremely significantdifferences in growth traits among families of different stand ages of P. massoniana. The family heritability of tree height, diameter at breast height and volume were all higher than the individual heritability. Compared with CK₁, CK₂ and the open-pollinated family population, the average real gains of tree height, diameter at breast height and volume of the four superior families were 9.51%～14.84%, 17.33%～29.06%, and 45.65%～93.41%, respectively, and the average genetic gains were 7.51%～11.73%, 14.38%～24.12%, and 38.80%～79.40%, respectively. The average real gains of tree height, diameter at breast height and volume of 12 superior individual plants were 27.78%～34.00%, 72.66%～ 89.93%, and 213.95%～316.90%, respectively, and the average genetic gains were 8.06%～9.86%, 19.62%～24.28%, and 70.60%～104.58%, respectively. The results will be benefit to improve the efficiency of superior variety selection and expanding the genetic gains of the breeding population of P. massoniana.