Abstract: The potted seedlings of Cupressus duclouxiana and Catalpa bungei were used to examine their response under different moisture content conditions, including normal moisture (25 %-30 %), moderate drought (15 %-20 %) and severe drought (5 %-10 %). The inoculated groups were the control group (A), VAM group (B), ectomycorrhizal(C) and mixture group (D, VAM+Ectomycorrhiza). After 150 days of treatment, the root biomass, root morphology and contents of nitrogen and phosphorus were measured. The results showed that after the seedlings were inoculated with mycorrhizal fungi, root biomass increased. The root biomass of Cupressus duclouxiana seedlings increased significantly under C and D treatments, however, B and D treatment significantly increased the root biomass of Catalpa bungei. Except severe drought,N and P contents in roots of Cupressus duclouxiana with mycorrhizal fungus inoculated were higher than those of control, whereas only with B and D treatment, the N and P contents of Catalpa bungei roots were higher than those of CK. After the seedlings inoculated with mycorrhizal fungi, the mean root diameter, total root length and root surface area of Cupressus duclouxiana increased; meanwhile, endomycorrhiza can positively affect the growth of the roots of Catalpa bungei seedlings.Our research showed that mycorrhizal fungus inoculation could enhance the drought resistence ability of Cupressus duclouxiana and Catalpa bungei seedlings in varying degrees.