This research is to study the distributive characteristics of soil microorganisms at river wetland on Mongolian Plateau in Inner Mongolia. The results showed that the quantities distribution of various floras of soil microorganisms in different plots (such as bump-top and in-between-bumps in enclosed and grazing regions, low floodplain and high floodplain) at wetland of the Xilin River are the same, which is bacteria＞actinomycetes＞fungi.In enclosed region, the amounts of bacteria are higher than that of other regions. Since is under natural restoration process in enclosed region, there is no significant difference between bump-top and in-between-bumps. At bump-top, it is seasonally flooded, and at in-between-bumps, there is always ponded water to cause high water content. Since high water content is not in favor to the survival of actinomycetes, the number of actinomycetes at bump-top is higher than that at in-between-bumps. Though there is low requirement of water for fungi, the number of fungi at bump-top is higher than that at in-between-bumps. In grazing region, there are more soil microorganisms at bump-top due to shorter flooded time and better air ventilation. At bump-top, organic matter is much richer, due to resupplied from animal manure, withered grass and falling leaves, which is in favor to the reproduction of actinomycetes and fungi. Since there are mostly hydrophilic plants and less biodiversity at in-between-bumps, the number of soil microorganisms is smaller. In floodplain region, the amount of bacteria at low floodplain is higher than that at high floodplain, due to higher water content, which is in favor to the reproduction of bacteria. Actinomycetes are basophilic bacteria. The amount of actinomycetes at low floodplain is higher than that at high floodplain, since high water content has led low floodplain to alkali soil. The amount of fungi at high floodplain is higher due to more suitable environment for survival and reproduction.