Abstract: In our research we probed the microbial community composition in near wellbore zone of injection wells and the influence that the different nutrition systems-stimulations have on the oil reservoir microbial metabolism and the displacement process. We investigated the microbial community construction and succession in flowback fluid samples from different stages by high-throughput sequencing and real-time PCR at first, and then we used laboratory shaking culture to detect the influence on indigenous microorganisms stimulation effect which made by flowback fluid samples of different stages, different nutrient types and oxygen supplements. Our results indicated that the composition of initial microbial community from the flowback fluid samples of different stages have significantly difference, and its dominant microbial community have similarity after the stimulation of same nutrition system. The stimulation level of hydrocarbon degrading bacteria such as Dietzia, Actinomycetes is closely related with oil emulsification effect. In the zone near injection wells, timely oxygen supplement is beneficial to emulsification, which is necessary to activate indigenous microorganisms and enhanced oil recovery. Compared with the amount of 16S rRNA、rhlAB、alkB genes, the amount of cyp153 gene and pH of stimulated samples are more suitable index to measure emulsifying effect in MEOR progess.