【Objective】This research aims to investigate the patterns of genetic variation in growth traits within a Sindora glabra provenance and family trial forest, determine the optimal age for early selection, and provide a scientific basis for selecting superior provenances and families. 【Method】Growth traits (tree height, DBH, crown diameter) were measured in 63 families from 6 provenances of S. glabra. Genetic variation in these traits was analyzed, and the efficacy of early selection was evaluated using principal component analysis at ages of 4, 5, 6, 8, and 10 years. 【Result】Significant differences (P<0.01) in tree height, DBH, and crown diameter were observed among provenances and families across all measurement ages. Phenotypic coefficients of variation (PCV) ranged from 24.63% to 39.13%, while genetic coefficients of variation (GCV) ranged from 7.83% to 16.65%. Family heritability (${h}_{f}^{2}$) and individual heritability (${h}_{i}^{2}$) for the traits ranged from 0.42 to 0.79 and 0.25 to 0.71, respectively. Heritability values gradually decreased and stabilized with increasing of tree age. Phenotypic and genetic correlations among traits were highly significant (P<0.01), but the correlation coefficients diminished as the time interval between measurements increased. Using the 10-year-old trees as the reference standard, early selection at 4 years old was found to be feasible. Thirteen superior families were identified, achieving actual gains in tree height, DBH, and crown width of 12.09% to 27.24% at age 10, with corresponding genetic gains of 5.08% to 20.08% over the five-year period. 【Conclusion】Provenances and families of S. glabra exhibit substantial genetic variation in growth traits. These traits display moderate to high family heritability and strong genetic correlations. Early selection at age four years shows promising accuracy, although further observation is warranted. Families No. 35, No. 62, and No. 45 are recommended as primary candidates for promotion.