Abstract: To study the effect of soil physical and chemical properties of different grassland types on the infection characteristics of AM fungi in Xiejiagou, through the investigation and sampling, the relationship between AM fungi infection situation and soil factors of 4 types of grassland (mountain meadow, meadow steppe, steppe and steppe desert) was studied. The results showed that the typical plants in the four grassland types could be infected by AM fungi, the average infection rate of mountain meadow, meadow steppe, grassland and steppe desert were 79.90%, 89.04%, 85.93% and 68.66%, respectively, meadow steppe was the grassland type with the best infection situation. The content of rhizosphere soil organic matter, available nitrogen, available phosphorus was positively correlated with AM fungi infection situation, salt content and pH were negatively correlated with AM fungal infection situation, but the infection rate and intensity reached the highest when salt content was around 2.1 g/kg. Under natural condition, soil factors were closely related to the infection and development of mycorrhizal, the level of soil nutrient restricted the infection of AM fungi, and organic matter and salinity were key influencing factors.