Backgrounds: Colorectal cancer (CRC) can be prevented and drastically reduced with colonoscopy. Whether Terminal ileal intubation (TII) is necessary for routine colonoscopy, and whether TII affects the adenoma detection rate (ADR) and the polyp detection rate (PDR), there is currently a lack of prospective studies. Methods: We retrospectively collected and analyzed data from patients who underwent colonoscopy at our hospital from June 1, 2020 to March 20, 2021, to evaluate the detection rate of intestine diseases diagnosed by TII, and to find factors related to ADR and PDR. Results: Among the 398 patients who completed cecal intubation (CI), TII was performed in a total of 207 cases (51.76%, 207/398), and no intestinal diseases were found. On univariable analysis, the TII/non-TII had no significant influence on PDR (49.8% vs. 57.6%, P>0.05) and ADR (30.4% vs. 28.8%, P>0.05). On multivariable analysis, Age, Sex, and colonoscopy withdrawal time (CWT) were independent positive predictors of polyps, while Age, Tobacco Use, and A.M. procedure were independent positive predictors of adenoma. Conclusion: These results highlighted Age and Sex as important risk factors for polyps and adenomas, and CWT as an important parameter to improve PDR and ADR. Meanwhile, the incidence of intestine disease was low in colonoscopy screening cases, where TII cannot improve the detection rate of intestinal disease nor help to improve ADR and PDR. Considering its cost-effectiveness, and the low prevalence of intestine disease, there is no clear evidence for the need to increase TII in routine colonoscopy without specific indications. We need to focus our limited efforts on factors that make sense for improving PDR and ADR, such as paying attention to male and senior patients and adequate CWT.