Patients with cholelithiasis (CL) or cholecystectomy (CE) would have more chances to get colorectal adenoma (CRA) or cancer (CRC). To figure out the effect of gut microbiota and bile acid on colorectal neoplasm in CL and CE patients, we executed a retrospective observational study recruited 463 volunteers, including 182 people with normal gallbladder (Normal), 135 CL and 146 CE patients. The discovery cohort was established to explore the difference of gut microbiota through 16S rRNA sequencing. The validation cohort aimed to verify the results of sequencing through qPCR. Through this research, significant enrichment ofEscherichia coliwas found in patients with cholelithiasis or cholecystectomy both in discovery cohort (PNormal-CL=0.013;PNormal-CE=0.042) and in validation cohort (PNormal-CLPNormal-CEEscherichia coliwas also increased in CRA and CRC patients (in discovery cohort,PHC-CRA=0.045,PHC-CRC=0.0016; in validation cohort,PHC-CRA=0.0063,PHC-CRC=0.0007). Pks+Escherichia coliwas found enriched in CL and CE patients in validation cohort (PNormal-CLPNormal-CEP=0.014; Ko00121 secondary bile acid biosynthesisP=0.010). In validation cohort, we also found the elevation of serum total bile acid of CE patients (P+Escherichia coli(r=0.1895,P=0.0012). In one word, our research found thatEscherichia coli, especially pks+species, was enriched in CL and CE patients. Pks+Escherichia coliand bile acid metabolism were associated with CRA and CRC in people after cholecystectomy.