Abstract: Objective To analyze the results of colonoscopy screening for colon cancer in middle aged and elderly people in a single center. Methods From January 2015 to December 2017, 96 352 patients aged 40 ~ 74 years were selected for colon cancer screening. The primary screening of colon cancer was carried out by means of risk assessment and two fecal immune fecal occult blood tests. The object of primary screening for high risk population was identified as positive screening, the colonoscopy was performed for fine screening diagnosis, biopsy was taken for the patients with pathological changes, and the results of tissue biopsy were used as the gold standard to analyze the results of screening. Results Among the 96 352 people who took part in the screening, 5078 were positive for primary screening, accounting for 5.3%, 47 153 were males and 49 199 were females, while 668 were males and 544 were females in 1 212 cases of colonoscopy. The rate of colonoscopy had no difference in male than female (22.6% vs 25.7%, P > 0.05), in which 40~49 years old (15.0%), 50 ~ 59 years old (28.9%), 60 ~ 69 years old (40.8%), 70 ~ 74 years old (15.3%). 1 212 cases did colonoscopy examination in 5078 cases, colonoscopy compliance rate (23.9%). The incidence of colonic polyps, colitis and colon cancer in the positive screening population was significantly higher than that in the female (P < 0.05). The incidence of colonic polyps, colitis and colonic cancer in different age groups were significantly different among the positive screening population (P < 0.05). The incidence of colonic polyps and colon cancer increased with the increase of age, and the incidence of colitis decreased. There were 30 cases (2.5%) of colon cancer in 1 212 patients who took part in colonoscopy, including 14 cases (46.7%) in the early stage and 16 cases (53.3%) in the middle and late stage. There were 9 cases (42.9%) in males and 5 cases (55.6%) in females. There was no significant difference between male and female (P > 0.05). Conclusion The colonoscopy screening results of middle and old people in our hospital showed that the incidence of colonic polyps, colitis and colon cancer in males was significantly higher than that in females. The incidence of colonic polyps and colon cancer increase with age.