Abstract: The effect of different protein, nonfibrous carbohydrates(NFC) and cellulose nutritious ingredient on bacterial community structure in rumen microenvironment was studied. The aim was to explore the fluctuation of predominant bacteria in rumens, and to understand clearly the dependence of rumen bacteria on nutrients. It provided foundation for further study on scientific nutrition ratio for supplementary feeding under the traditional grazing and large scale breeding. Experiment was divided into 2 groups under traditional grazing and TMR fodder feeding, at each of which there were 10 Pengbo semi-fine wool ewes (2-year-old, 2 repetitions in each group, (23.77±2.34) kg of weight). The Kjeldahl, van soest and difference methods were used to determine the crude protein, cellulose and NFC content of forage grass mixed forage in the grazing group and forage in the feeding group. After half a year of feeding, the rumen fluid was extracted, the total DNA was extracted, and a recombinant standard plasmid was constructed to perform absolute fluorescence quantification(qRT-PCR) study on rumen bacteria. The results showed that:1) At the level of phylum, the preponderant population was Bacteroidetes, its abundance in grazing group((49.52±6.07)%) was 6.00% fewer than that in barn feeding group((55.52±12.18)%), but the difference was not significant (P>0.05). The abundance of Firmicutes in grazing group((43.28±4.59)%) was 6.60% higher than that in barn feeding group((36.68±9.78)%), the difference was significant(P<0.05). The abundance of Spirochaetes in grazing group((1.99±1.75)%) was 1.23% higher than that in barn feeding group((0.76±0.59)%), the difference was significant(P<0.05). 2) Analysis by PLS-DA and LEfSe revealed that the main bacteria that showed significant differences between the 2 groups were:the cellulose or its metabolites mainly depended on Pseudobutyrivibrio, Selenomonas, Coprococcus, Clostridium, Anaerovibrio, Shuttleworthia, CF231, Butyrivibrio, YRC22, Lachnospira, Moryella(in grazing group). The high-protein and NFC (in barn-feeding) or their metabolites mainly depended on Desulfobulbus, Atopobium, p-75-a5, Prevotella, Blautia, Ruminococcus and Streptococcus(in barn feeding group). The results indicated that the reasonable protein and energy levels in diet was not only beneficial to the proliferation of protein and starch-dependent bacteria, but also to the proliferation of main fiber-degrading bacteria (Ruminococcus) and synergistic fiber-degrading bacteria (Prevotella). Meanwhile, the abundance of cellulose decomposing bacteria (Firmicutes and Spirochaetes) had all declined obviously in barn feeding group.