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Based on the polymerase chain reaction - denaturing gradient gel electrophoresis (PCR- DGGE) and sequence analysis, two herbicide tolerant genetically modified soybeans ( PAT, ALS ) and the corresponding non - transgenic soybeans (PAT1, ALS1 ) and the local main non - transgenic soybean (Zhonghuang 13, CK) were selected to investigate the effects of herbicide tolerant transgenic soybean cultivation on nitrogen - fixing bacteria in rhizosphere under field experiment. The results showed that the community composition similarity of soil nitrogen -fixing bacteria between transgenic soybean ( PAT, ALS ) and the corresponding non - trans genic soybean ( PAT1,ALS1 ) was approximately 60% . Compared to the corresponding non - transgenic soybeans (PAT1, ALS1), the diversity index (H) and evenness index (EH) of nitrogen - fixing bacterial nifH genes in rhizoshpere of herbicide tolerant genetically modified soybeans (PAT, ALS) both showed no significant difference (p >0. 05) . The sequen-cing and phylogenetic analysis indicated that nitrogen - fixing bacterial nifH genes in rhizoshpere of herbicide toler-ant genetically modified soybeans ( PAT, ALS ) and the corresponding non - transgenic soybeans ( PAT1, ALS1 ) mainly belonged to cyanobacteria, Proteobacteria and Firmicutes. Nitrogen - fixing microbial communities were sig-nificantly (p <0. 05) influenced by the levels of the available phosphorus ( AP) and nitrate nitrogen ( N03 - N) when canonical correspondence analysis was used to identify relationship between nifH gene and soil physicochemi-cal factors. This result indicated that herbicide tolerant genetically modified soybeans had no significant effects on the diversity of soil nitrogen - fixing bacterial nifH genes in rhizosphere. [ABSTRACT FROM AUTHOR]