To evaluate the effects of abdominal belts in colonoscopy for patients with low body mass index (BMI) (BMI<18.5 kg/m2) or a history of abdominal surgery, a prospective, randomized, single-blind study was conducted on colonoscopy outpatients. Patients with low BMI or a history of abdominal surgery who underwent colonoscopy at the Second Affiliated Hospital of Soochow University from January 2018 to January 2022 were enrolled. The patients were divided into the abdominal belts group and non-abdominal belts group according to whether they used abdominal belts. Differences between the two groups were compared in terms of cecal intubation time, length of colonoscope intubation into the cecum, patient repositioning, abdominal pressure, and degree of abdominal distension. A total of 296 patients (98 low BMI patients and 198 patients with a history of abdominal surgery) were enrolled, 148 in each group. The results showed that cecal intubation time (4.35±1.85 min VS 7.99±3.86 min, t=35.624, P<0.001) and length of colonoscope intubation into the cecum (72.03±10.35 cm VS 86.42±17.71 cm, t=38.442, P<0.001) were lower in the abdominal belts group, compared with those of the non-abdominal belts group. The percentage of patients requiring repositioning [18.9% (28/148) VS 71.6% (106/148), χ2=82.959, P<0.001] and abdominal pressure [6.1% (9/148) VS 52.7% (78/148), χ2=77.504, P<0.001] in the abdominal belts group were significantly lower than those in the non-abdominal belts group. There were significant differences in the degree of abdominal distension during and after colonoscopy ( P<0.001). In conclusion, the use of abdominal belts significantly improves the efficiency and effects of colonoscope intubation in difficult colonoscopy patients with low BMI and a history of abdominal surgery.