Objective To study the function of the RNA-binding protein Hfq in Bacillus subtilis cellulose decomposition. Results In the medium with sodium carboxymethylcellulose (Na-CMC) as the sole carbon source, the knockout of Hfq resulted in a 38.0% +/- 2.1% and 76.6% +/- 7.1% decrease in cellulose hydrolysis ability and cellulase activity, respectively. The results of real-time quantitative PCR revealed that several cellulase genes (eglS, bglA, and bglC) were significantly downregulated in the Hfq knockout strain. The isogenic Delta hfq complemented strain recovered the cellulose hydrolysis ability, cellulase activity, and expression level of cellulase genes. In addition, the survival of Hfq mutant in stationary phase was significantly affected. Conclusion RNA-binding protein Hfq is involved in the regulation of cellulose hydrolysis ability, cellulase activity, cellulase gene expression, and stationary phase survival.