Abstract: In order to study the genetic variation of half-sib families of Toona sinensis from the seedling stage, and 18 one-year container seedlings of Toona sinensis superior half-sib families from three main distribution areas in Sichuan province were taken as the research object, and the seedling growth comparison and superior family selection were carried out. The results showed that the seedling height has a significant positive correlation with latitude and annual average temperature, and an extremely significant negative correlation with altitude, while ground diameter had no significant correlation with various environmental factors. The seedling height and ground diameter varied from 38.1 cm to 101.6 cm and from 4.42 cm to 9.14 mm respectively, with significant differences among different families. The variation coefficients of seedling height and ground diameter of most families were less than 15%, and the growth of seedlings was uniform. The heritability of seedling height and ground diameter were 0.939 and 0.762 respectively, and the genetic regulation of seedling height was greater than that of ground diameter. Three superior families, Pengxi 1, 5 and Hejiang 7 were selected, with a selection rate of 16.67%, and the genetic gains of seedling height and ground diameter of the selected families were 35.33% and 20.19%, respectively. The selection deviation of selected families was big, the selection rate was low, and the genetic gain was large. After afforestation comparative test, the selected families had the potential to become good varieties.