Object The quality of bowel preparation is the key to colonoscopy. Effective bowel preparation can reduce the rate of missed diagnosis and improve the detection rate of intestinal diseases. The purpose of this study is to investigate the influencing factors of oral administration of compound polyethylene glycol on bowel cleaning quality. Methods From March 2016 to November 2016 to November 2016, the patients who underwent colonoscopy in our hospital and met the criteria for admission were enrolled in our study. The intestinal Boston rating scaleon left colon, transverse colon, right colon and the whole colon were recorded for each patient. The height, weight , age, the diet a day before the colonscope, the dose, time ,total dosing time of polyethylene glycol electrolyte powderthe first defecation time, the total defecation frequency , the interval from the first dose to the first defecation, the interval from the first dose to colonscope were recorded , too., The cumulative odds logit model and the trend chi square test were used for statistical analysis. The statistical significance of P<0.05 was statistically significant. Result There were 155 patients enrolled in the study. The cleanliness of left colon (X2=6.276,P=0.012), transverse colon (X2=6.302,P=0.012), right colon (X2=4.068,P=0.044), the whole colon (X2=6.264,P=0.012), no matter the patients have strict Restricted diet or not ,had significant difference ;The cleanliness score of left colon when the patients had more than 10 times defecation were significantly higher than other patients (X2=4.209,P=0.040), but there was no difference in cleanliness between the right colon and transverse colon; The cleanliness of the left colon (X2= 3.909,P=0.048)), transverse colon (X2=4.732,P= 0.030), right colon (X2=6.562,P= 0.010) and the whole colon (X2=5.507,P= 0.019) had significant differences comparing the patients whohad the less than 500 minutes interval from the first dose to colonscope than other patients. others. The cleanliness score of the right colon, whose interval from first dose to first defection was more than 60 minutes was obviously lower than the other patients’(X2=4.753,P= 0.029). However, there is no difference in cleanliness of left colon and transverse colon. Conclusion Diet control of patients, the interval from taking compound polyethylene glycol to the first defecation, defecation frequency, and the interval from taking medication to colonscope, should be individualized and standardized into bowel preparation program.Strengthen the observation and record of defecation to improve intestinal cleaning quality.