Objective This study aims to investigate the genetic variation patterns of growth traits in superior tree progeny of Semiliquidambar cathayensis during the young forest stage, and to screen elite breeding resources.

Methods Sixty superior tree progenies of S. cathayensis collected from Fujian and Hunan Provinces were introduced to Jingning County, Zhejiang Province for progeny testing. Genetic variation patterns were analyzed, genetic parameters were estimated, and superior families and individuals were selected.

Results The phenotypic variation coefficients for tree height, diameter at breast height （DBH） and current annual increment of 3-year-old S. cathayensis ranged from 35.52% to 52.85%, while the genetic variation coefficients ranged from 13.40% to 16.36%, indicating high selection potential. The family heritability of each trait ranged from 0.78 to 0.85, suggesting strong genetic control. Using the selection index method with a selection rate of 10%, six superior families were identified, with genetic gains for DBH, height and current annual increment ranging from 23.44% to 43.23%, 21.39% to 29.21%, and 13.12% to 36.44%, respectively. Thirty-one superior individuals were selected at a selection rate of 1%.

Conclusion The growth traits of 3-year-old S. cathayensis superior tree progeny exhibit rich variation. On the basis of the combined strategies of family and individual selection, superior families and individuals with significant growth advantages can be successfully identified, thereby providing high-quality germplasm resources for the breeding of this species.