The effects of AM fungi on the growth and drought resistance of greenhouse grown Caragana korshinskii inoculated Glomus mosseae or native fungi in the rhizosphere of Caragana korshinskii were studied at three water treatments levels of 80％、60％ and 40％ water added to the soil for the potted plant. The results showed that application amount of water significantly influenced the growth of host plants and inoculation effects of AM fungi. Mycorrhizal infection rate was promoted by inoculation AM fungi under different soil water contents. The height, stem thickness and total dry weight of plants were increased, the utilization of available N and P in soil, complete P content in host plant and water preservation in leaves were enhanced by inoculation AM fungi under applying 40%～60% water content. The content of chlorophyll, soluble sugar and activity of protective enzymes, such as SOD, POD and CAT significantly increased. The content of MDA significantly decreased by inoculation AM fungi under applying 40% water content. The best inoculation effect was native fungi in the rhizosphere of Caragana korshinskii under soil water stress. It could be concluded that the mechanism of AM fungi strengthening the drought resistance of Caragana korshinskii may be the direct role of AM fungal hyphal contribution to soil water and minerals uptake in mycorrhizal plant, and the indirect role of AM fungi improved the water status and physiological metabolic activity and enhanced the activity of protective enzymes of mycorrhizal plant.