To gain a better understanding of genetic variation of growth traits in Larix olgensis, we investigated the progeny of 60 half-sib families of L. olgensis grown in a seed orchard in northeastern China. Tree height (H), basal diameter, and diameter at breast height (DBH) were measured at four different ages (i.e., at 4, 6, 8 and 10 years of growth). Significant differences among all the variation sources were observed during the different growth years. During the four measured years, phenotypic coefficients of variation (PCVs) of all traits ranged from 17.83 to 33.01 %, with heritabilities varying from 0.531 to 0.798. A correlation analysis uncovered extremely significant positive correlations among all traits within or among years. These high heritabilities and large PCVs were beneficial for the early selection of superior families. Using a comprehensive evaluation method, different families were selected as superior on the basis of different selection rates during each measured year, with families L78, L64, L63, L48, L13 and L14 selected across all measured years. At the 10th growth year, the optimal time to identify superior L. olgensis families, the selected families (L78, L64, L63, L48, L13 and L14) displayed higher H and DBH values, which corresponded to genetic gains of 8.31 and 16.82 %, respectively. In addition to the identification of superior female parents for improved seed orchard establishment, the findings generated by our study can serve as a theoretical foundation for early selection of L. olgensis families.