Abstract: The study showed that through 17 years of mowing, the soil microbial quantity and underground plant biomass in the Xilinguole Leymus chinensis steppe of Inner Mongolia were decreased with increasing mowing frequency. Based on the variation of soil microbial quantity and underground plant biomass under effects of mowing frequency, it was suggested that one year cutting and one year no cutting,or two years’ cutting and one year no cutting would be the more reasonable mowing frequency, while fencing too many years would not only lead to the waste of pasture resources, but also weaken the effects of soil microbes on soil nutrients transformation.

Key words: Loess hilly and gully region, Alfalfa, Soil water