The study assesses the spatio-temporal distribution of AM fungi and the relationships between AM fungi and soil factors by analyzing soil samples collected at Shapotou of Ningxia. Soil samples in the rhizosphere of Ammopiptanthus mongolicus (Leguminosae) were divided to a depth of 50 cm into 5 sections of 10 cm each. Four replicates at each depth were taken during May, August and October 2007. Three genera and 12 species of AM fungi were isolated from the soil samples: Gigasporn, 6 species; Acaulospora, 4 species; and Scutellospora 2 species. All were collected in every sampling period. The greatest spore density and vesicular colonization levels were found in August, and the highest arbuscular, hyphal and total colonization levels were found in October. Soil sampling depth had a significant effect on spore density and percent colonization levels of AM fungi. The greatest colonization and spore density levels were found in the first three layers, between 0-30 cm. Spore density had a positive correlation with soil organic matter, available N and pH. Hyphal and total colonization had a positive correlation with soil pH, available N and P. The distribution and colonization of AM fungi is a useful indicator for monitoring the changes of a desert soil ecosystem and evaluating the ability of mycorrhizae to form a relationship with the host plant.