Abstract: Seed vitality index can be applied to predict seed germination rate and seedling growth, which is usually taken as a very important evaluation index for seed trees in seed orchard. In this experiment, a comparative study on seed vitality and seedling growth characteristics of Betula pendula families was conducted by taking 15 triploid families and 1 diploid family as control collected from the triploid seed orchard as objects. The results of variance analyses showed that there were significant differences in each of the seven traits (one thousandseed weight, main seed vitality traits and vitality indexes among these families (sig.＜0.01). According to the seven indexes including germination potential, germination index, vitality index and robustness rate of seedlings, an integrated evaluation on the families was made by using the method of membership function value in Fuzzy mathematics. The result was that only 3 triploid families were superior to the diploid control, and the seed trees of the 3 superior triploid families were preliminarily selected to be first choice maternal trees for rebuilding the triploid seed orchard.