Abstract: To investigate and evaluate the seedling growth performance half-sib families progenies of Pinus yunnanensis, the seeds of P. yunnanensis with two phenotypes of straight and twisted stem were collected from Xinping of Yunnan province as experimental materials for sowing and breeding. The seedling height and ground diameter growth of the progenies of P. yunnanensis in 49 families were measured and analyzed. The variation coefficients of seedling height and ground diameter in the two types of P. yunnanensis were 27.81%, 31.26% and 43.55%, 43.85%, respectively, and the differences of seedling height and ground diameter between the two kinds of families were extremely significant. In addition, the heritability of seedling height in P. yunnanensis with straight stem and P. yunnanensis with twisted stem was 0.93 and 0.91 respectively, while the heritability of ground diameter in the two types of P. yunnanensis 0.98 and 0.93 respectively. And, the average expected genetic gain of 11 families with better performance in seedling height was 8.48%, while that of 12 families with better performance in diameter was 11.52%. The average expected genetic gain was 36.03% for 6 families with better growth performance in seedling height and 15.26% for 9 families with better growth performance in diameter of P. yunnanensis with twisted stem. The abundant variation provided the basis for the selection of superior families and the identification of superior varieties, and the higher heritability indicated that the growth of seedlings in different families was controlled by genetic factors, which provided reliable guarantee for the selection of superior families.