Objective To comprehensively evaluate the quality of colonoscopy in Endoscopy Center of Gansu Provincial Hospital, and to provide baseline data and theoretical basis for evaluating the quality of digestive endoscopy in China. Methods It is a single-center, retrospective and cross-sectional study. Data were collected from patients who underwent colonoscopy and received therapies in the Endoscopy Center of Gansu Provincial Hospital from 1st January to 31st December in 2021. The quality control indicators including polyp detection rate, adenoma detection rate, cecal intubation rate, and adequate intestinal preparation rate were analyzed to evaluate the quality of colonoscopy in the endoscopy center. Results A total of 7 562 patients who underwent colonoscopy were included in this study, with the age of (51.61±13.59) years, including 4 286 males (56.7%) and 3 276 females (43.3%) . There were 4 924 (65.1%) outpatients and 2 638 (34.9%) inpatients. Procedures were completed by full-time endoscopists on 6 456 patients (85.4%) , and those were by gastroenterologists or proctologists on 1 106 patients (14.6%) . The overall adenoma detection rate, polyp detection rate, cecal intubation rate, and adequate intestinal preparation rate were 11.9% (900/7 562), 32.9% (2 488/7 562), 93.0% (7 030/7 562), and 91.3% (6 906/7 562) respectively. The male, the elder, in patients, and examined by full-time endoscopists were associated with higher adenoma detection rate and polyp detection rate with significant difference (P<0.05). Conclusion The cecal intubation rate and adequate intestinal preparation rate of colonoscopy in Gansu Provincial Hospital could meet the guideline standard, but the adenoma detection rate still needs to be further improved. The elder and male patients are the key population for colonoscopy screening. In addition, great importance should be attached to the standardized training of endoscopists to further improve the quality of colonoscopy.The quality control indicators such as polyp detection rate, adenoma detection rate, cecal intubation rate, and intestinal cleansing rate were analyzed to evaluate the quality of colonoscopy in the digestive endoscopy center of our hospital. Results A total of 7562 patients with colonoscopy were included in this study, with an average age of ( 51.61±13.59 ) years, including 4286 males ( 56.6 % ) and 3276 females ( 43.3 % ). 6456 cases ( 85.3 % ) were completed by full-time endoscopists, 1106 cases ( 14.6 % ) were completed by part-time endoscopists, and 4924 cases ( 65.1 % ) were outpatients. The overall adenoma detection rate, polyp detection rate, cecal intubation rate, and intestinal cleansing rate were 11.9 % ( 900 / 7562 ), 32.9 % ( 2488 / 7562 ), 92.9 % ( 7030 / 7562 ), 91.3 % ( 6906 / 7562 ). The sex, age, source of patients and endoscopic operators were compared in groups,showing that male, elder, hospitalized patients, and full-time endoscopists were associated with higher adenoma detection rate, polyp detection rate , and the results were statistically significant ( P < 0.05 ). Conclusions The cecal intubation rate and adequate bowel preparation rate of colonoscopy in our hospital met the guideline standards．But the adenoma detection rate still needs to be further improved. The elder and male patients are the key population for colonoscopy screening. In addition, emphasizing on standardized training of endoscopy physicians is also an important link to further improve the quality of colonoscopy.