Objective To explore the effects of warm water insufflation applied in difficult colonoscopy on its success rate, insertion time, operation difficulty level and tolerance of patients. Method 200 cases of the difficult defecation of non-narcotic colonoscopy, IBS and always has a history of pelvic/abdominal surgery patients, were randomly divided into warm water infusion group (experimental group) and traditional method of air insufflation group (control group), then compare the differences of the success rate of the two groups of patients, the insertion time and degree of tolerance in patients. Results All the patients completed the investigation in this study, neither bowel perforation nor other complications occurred. Experimental group success rate of the whole colon examination, the insertion time, the operator satisfaction and check again wishes were significantly higher than that of control group (P < 0.05). In abdominal pressure and utilization, abdominal pain scoring position transformation, the former was significantly lower than the latter (P < 0.05). In abdominal pressure and utilization, abdominal pain scoring position transformation, the former was significantly lower than the latter (P < 0.05). There is no significant difference (P > 0.05) in Polyp detection rate. Conclusion Warm water insufflation colonoscopy can effectively improve the tolerance and accelerating the colonoscopy in patients with difficult insertion process, improve work efficiency, and is an ideal method, which is worth of promoting.