Subject: The dysbiosis of gut microbiota is pivotal in colorectal carcinogenesis. However, the synergy between an altered gut microbiota composition and differential gene expression of specific genes in colorectal cancer (CRC) remains elusive. Method: The gut microbiota dataset with number SRP158779, which contained 19 CRC samples and 19 normal samples, was downloaded from the National Center for Biotechnology Information (NCBI) Sequence Read Archive (SRA) database. The 16S rRNA gene sequences from this dataset were clustered into operational taxonomic units (OTUs); thereafter, the OTUs that were differentially enriched in CRC were identified and classified, followed by prediction of their functions. Additionally, RNA sequencing data from CRC samples was obtained from The Cancer Genome Atlas project (TCGA), and the differentially expressed genes (DEGs) and enriched pathways were identified. Finally, similar pathways that were significantly enriched in both differential OTUs and DEGs were screened. Key genes related to these pathways were executed the prognosis analysis. Results: The presence of Proteobacteria and Fusobacteria increased considerably in CRC samples; conversely, the abundance of Firmicute and Spirochaetes decreased markedly. In particular, the genera Fusobacterium , Catenibacterium , and Shewanella were detectable in tumor samples. Moreover, 246 DEGs were identified between tumor and normal tissues. Both DEGs and microbiota were involved in bile secretion and steroid hormone biosynthesis pathways. Finally, CYP3A4 and ABCG2 expression in CRC was related to the prognostic outcomes of CRC patients. Conclusion: Identifying the complicated interplay between gut microbiota and the DEGs could help in further understanding the pathogenesis of CRC, and these findings would enable better diagnosis and treatment of CRC patients. Keywords: colorectal cancer, gut microflora, gene expression, pathways enrichment, survival analysis