Objective To explore the effect of combined polyethylene glycol electrolyte powder and Chaishaochengqi decoction in bowel preparation before painless colonoscopy,aiming to improve patient compliance and bowel preparation quality.Methods A total of 519 patients scheduled for painless colonoscopy were randomly divided into the observation group and the control group.The observation group took polyethylene glycol electrolyte powder 68.56 g(1000 mL)and Chaishaochengqi decoction 1 dose(160 mL)orally at 20:00 the day before the examination;and polyethylene glycol electrolyte powder 68.56 g(1000 mL)again at 4:00 on the day of the examination.The control group took polyethylene glycol electrolyte powder 137.12 g(2000 mL) orally at 20:00 the day before the examination,and polyethylene glycol electrolyte powder 68.56 g(1000 mL)again at 4:00 on the day of the examination. Painless colonoscopy was performed 6 hours after completing bowel preparation.The differences in bowel preparation cleanliness score,adequate bowel preparation rate,colon polyp detection rate,number of colon polyps detected,patient adverse reactions,and acceptance of repeat bowel preparation between the two groups were compared.Results The total Boston score and the rate of adequate bowel preparation in the observation group were significantly higher than those in the control group,and the bowel scores of each segment in the observation group were all higher than those in the control group,with statistically significant differences(P<0.05).The polyp detection rate in the observation group was 33.5%,higher than the control group's 29.4%,but the difference was not statistically significant(P>0.05).The number of polyps ≤5 mm in the observation group was higher than that in the control group,with statistically significant differences(P<0.05).The proportion of patients with abdominal pain and bloating in the observation group was significantly lower than that in the control group(P<0.05),there was no statistically significant difference in the acceptance of repeat bowel preparation between the two groups(P>0.05). Conclusion The combined use of polyethylene glycol electrolyte powder and Chaishaochengqi decoction for bowel preparation can significantly improve the effect of bowel preparation.