Biodegradation by autochthonous microbial community is an important way to clean up nonylphenol (NP) from contaminated river sediment. Knowledge of sediment microbial community can aid in our understanding of biological processes related to NP degradation. However, the change in sediment microbial community associated with NP biodegradation remains unclear. The present study investigated the shift in bacterial community structure and NP-degrading gene abundance in response to NP attenuation in river sediment. Sediment microcosms with different levels of 4-NP (0, 100, or 300 mu g/g) were constructed. A nearly complete attenuation of NP occurred in the microcosm with 100 mu g/g NP after 9 days' incubation, while a residual NP rate of 8.1 % was observed in the microcosm with 300 mu g/g NP after 22 days' incubation. Illumina MiSeq sequencing analysis indicated that Gammaproteobacteria, Alphaproteobacteria, and Bacteroidetes predominated in NP-degrading river sediment. Sediment bacterial community structure varied significantly during NP biodegradation and subsequent incubation, which was affected by the level of added NP. The n-alkane biodegradation (alkB) gene abundance showed a significant variation in each NP-amended microcosm (100 or 300 mu g/g), while a significant increase in the single component monooxygenase (sMO) gene abundance only occurred in the microcosm spiked with 300 mu g/g NP. This study can provide some new insights toward NP-degrading microbial ecology in the environment.