Abstract:The effects of AMF alkaline phosphatase(ALP)activities on Hippophae rhamnoides drough-resistance under water stress condition were studied with the histochemical techniques．The result shows in the mycorrhizae the total hyphae and functional hyphae form the base for the active hyphae，and amounts follow the order of total hyphae>functional hyphae>active hyphae．Active hyphae play an important role in the biomass accumulation of the hosts；the hyphae with phosphatase activity have a positively strong effect on Hippophae rhamnoides growth and its drought-resistance，and with the rise of ALP，the fresh weight of the host trees increases and wilting coefficient lowers．The direct participation of ALP in the exchanges of P nutrient substance of host trees can improve the nutrient and water condition，and raise the drought-resistance of the trees as well．