Abstract: Populas hopeiensis Hu et Chow is a tree species with very low rootbility. We had extracted endohormone from its buds and cortical layers and had carried out biological determination and gaseous phase determination. The result shows:1. Hebei poplar cuttings contains many kinds of active root inhibition materials, mainly ABA. Its content in the bud is higher than in the cortical layer.2. The content of ABA is variable according to the changes of season: From rest period to the period of germination, ABA content in the buds are from 535ng/g, fresh weight decreasing to 29.5ng/g; ABA content in the cortices are from 230ng/g decreasing to 19ng/g. But its GA₃ and IAA contents are presented a picture of curve variation.3. The survival rate of Hebei poplar is low. The root inhibition material in the cutting to hampers the growth and development of the cutting's root primordium.4. We adopt the way of soaking the cuttings in the water. In autumn, the artificial defoliation will be shifted to an earlier time; in winter, We store the cuttings under low temperature. All the abovementioned ways of treating cuttings will regulate the proportional relationship of the two matters existing in the cuttings. They are beneficial to raise the survival rate of the cuttings.5. The application of exo-hormone will raise the healing ability of the tissues, and it will promote the activities of peroxidase and isoenzyme, thereby increasing the rootability of the cuttings. If the cuttings are treated with NAA, HA,and RM₃ in combination, the enzume activity will raise by 37%; or if the cuttings are treated separately with NAA or HA, the enzyme activity will raise only by 8%.