[Background] Soil microbe is an important part of grassland ecosystems, and it plays an irreplaceable role in regulating plant growth, promoting the formation of soil structure, and maintaining the function and stability of grassland ecosystems. [Objective] To explore the diversity of microbial community metabolic function in rhizosphere soil of five different plants in two different grasslands in Siziwang Banner of Inner Mongolia. [Methods] Biolog-ECO microplate method was used to analyze microbial community diversity in rhizosphere soil of Stipa breviflora, Artemisia frigida, Convolvulus ammannii, Heteropappus altaicus and Allium tenuissimum in the 2 plots of Adege and Gentala in Siziwang Banner. [Results] There are significant differences in the number of culturable microorganisms in the rhizosphere soil of 5 different plants in two different grasslands (P<0.05). The total number of culturable microorganisms in S. brevifolia in Adege grassland is significantly higher than that of other plants. The total number of cultivable microorganisms in the rhizosphere soil of H. altaicus in the Gentala grassland was significantly higher than that of other plants. The average color change rate (AWCD) of rhizosphere soil microbes of different plants in the two grassland showed that the AWCD of rhizosphere soil in Gegentala grassland was higher than that in Adege grassland, and showed “S” type change. After 96 hours of cultivation, the Shannon index and Simpson index of the five plants in the Gentara grassland were higher than those in the Adege grassland, and the microbial diversity index of the rhizosphere soil of C. ammannii was very different in the two grasslands. The utilization of carbon sources by soil microorganisms is mainly amino acids and carbohydrate carbon sources, and it is significantly enriched for functional microorganisms such as L-asparagine, r-hydroxybutyric acid, L-serine and D-galacturonic acid. AWCD of rhizosphere soil microorganisms and diversity index of bacteria, actinomycetes and total number of soil microorganisms have a very significant positive correlation (P<0.01). Evenness index and total number of bacteria, actinomycetes and soil microorganisms have significantly negative correlation (P<0.05). [Conclusion] different plant rhizosphere soil microorganisms had different utilization and preference of carbon source. The number of microorganisms in rhizosphere soil was higher, the microbial carbon metabolism capacity and microbial community diversity was more abundant.