Abstract: The research is conducted at a degraded steppe in Hebei province, China. Researchers took four sample areas which are dominated by fringed sagebrush (Artemisia frigida), narrowleaf stellera (Stellera chamaejasme), shining speargrass (Achnatherum splendens), white swordflag (Iris lactea), respectively. Phosphorus (P) was applied at four levels (0, 5, 10 and 15 mg kg-1 soil) in each sample area. The AM fungi colonization and the organic acid exudation in the rhizosphere were affected by the concentration of soil available phosphorus. These results suggested that the difference of soil P content is probably the cause of the appearance of four patches.