In this research,the effect of the different growth regulating substances on the somatic embryogenesis of U1mus macrocarpa var.mongilica was studied by the matured embryo as explants,and the histological characteristics in the somatic embryogenesis process were observed by the paraffin slice.The results show that the optimum medium is MS + 1.0mg·L-12,4-D+0.5mg·L-16-BA for the induction of embryogenic callus;MS + 1.0mg·L-16-BA + 2.0mg·L-1IAA + 400mg·L-1Hydrolyzed milk protein is for inducing somatic embryos.The somatic embryos with a small amount of callus can be cultivated in the new medium of the somatic embryo induction for the proliferation.The somatic embryogenesis experienced 4 stages: the globular embryo,the heart-shaped embryo,the torpedo-shaped embryo and cotyledon embryo period,and has the integrity of the embryo structure on histological observation.