The mutual effect of gene type and circumstances often caused notable increase or decrease of production. The adaptability and stability analysis on introduced families of loblolly pine in Fujian Province indicated that there were significant differences in families, sites, gene and site mutual variance. The environment indexes of 3 sites all reached significant level. Yangkou site was propitious to the growth of diameter at breast-height and volume. Nanyu site was propitious to the growth of height, but the environment indexes of Nanan were all negative. The preceding 5 families which mutual variance were big in height were No. 23, 20, 15, 16, 3 and in diameter at breast-height were No. 24, 15, 3, 23, 22. No. 24, 23, 20, 22 and 3 families were very steady in biology. No. 11, 12, 13, 15, 18, 19, 21 and 25 families had wide adaptability, No. 16, 17, 20, 22, 23 and 24 families only grew well in fine environments. No. 8, 6, 4, 9, 1 and 2 families were not sensitive to environment change, and they had stability of agronomy.