Different species of stock seedlings differ in root morphology, which have significant influences on the early growth phases of the planted forest and the stability of the established ecosystems. Taking Platycladus orientalis and Ulmus pumila as examples, the study investigated the root growth of both seed-base and container seedlings 18 months later after they were planted. The obtained results indicated that, the total root length and average root diameter of P. orientalis transplants of the seed-base seedlings were 316.20 cm and 0.05 mm bigger than that of the container seedlings，while the total root length and average root diameter of the U. pumila transplants of the seed-base seedlings were 651.54 cm and 088 mm bigger than that of the container seedlings, respectively. The root surface area of the P. orientalis and U. pumila transplants of the seed-base seedlings were 40.05% and 73.04% larger than that of the container seedlings. No evident difference in the total root volume between the P. orientalis transplants of the seed-base seedlings and that of the container seedlings. by contraries, the total root volume of the U. pumila transplants of the seed-base seedlings was 54.70% bigger than that of the container seedlings. Numbers of the first lateral roots of the P. orientalis and the U. pumila transplants of the container seedlings were 42.31% and 30.65% correspondingly bigger than that of the seed-base seedlings. Root tip number of the P. orientalis transplants of the container seedlings was 324 more than that of the seed-base seedlings, while that difference between the U. pumila transplants of both two kinds of the seedlings was not significant. In every treatment, a significant relationship between the total root length and the root surface area was found. No significant relationship, however, was detected between the total root length and the root total volume. Average root diameter and root tip number of the transplants of the container seedlings were independent. Contrarily, average root diameter of the transplants of the seed-base seedlings showed significant relationships with both the total root length and the root total volume. It could be concluded that, Seed-base could increase the root:shoot ratio and stimulate the growth of seedling height, root collar diameter and root dry weight. Thus, young trees transplanted using seed-base seedlings could have bigger potentials to absorb water and fertilizer, and to immobilize topsoil.