Objective To investigate the change of the detection rate of colorectal cancer (CRC), colorectal adenoma and advanced adenoma in adults under colonoscopy in Shihezi in the past ten years. Methods Data of patients who completed colonoscopy in the First Affiliated Hospital of Shihezi University School of Medicine from January 1, 2010 to December 31, 2019 were investigated. The medical records were collected by consulting the electronic medical record system, including the age and sex of patients and the location, quantity, size and pathological type of lesions. The detection rates, including the overall detection rate in the past 10 years, those in the first 5 years (from 2010 to 2014) and the second 5 years (from 2015 to 2019) of colorectal adenomas, advanced colorectal adenomas and CRC, were studied. Results A total of 50 645 cases were included, 14 931 cases were excluded by the exclusion criteria, and finally a total of 35 714 cases were included in the data analysis. The 10⁃year overall detection rates of colorectal adenoma, advanced colorectal adenoma and CRC were 17.65% (6 302/35 714), 4.45% (1 589/35 714) and 3.71% (1 324/35 714), respectively. The overall detection rates of colorectal adenoma and advanced colorectal adenoma in the second 5 years were higher respectively than those in the first 5 years [20.33% (4 565/22 457) VS 13.10% (1 737/13 257), 4.69% (1 053/22 457) VS 4.04% (536/13 257)]. The overall detection rate of CRC in the second 5 years [3.30% (741/22 457)] was lower than that in the first 5 years [4.40% (583/13 257)]. Conclusion Compared with 2010 to 2014, the detection rate of colorectal adenoma in Shihezi area in 2015 to 2019 increased significantly, the detection rate of advanced colorectal adenoma increased slightly, and the detection rate of CRC decreased slightly. Therefore, the detection and resection of colorectal adenoma by colonoscopy may be important in reducing the incidence of CRC.