Objective To evaluate Bristol Stool Form Scale (BSFS) in the quality assessment of bowel preparation for colonoscopy in the elderly, and determine the effectiveness and tolerance of our intensive bowel preparation for those with Bristol stool types 1 and 2. Methods A total of 240 patients who made an appointment for colonoscopy in our endoscopy center from March to December 2019 were enrolled in this study. The patients with Bristol stool types 1 and 2 were randomly divided into group A and group B, and the other with types 3-7 into group C. The patients from groups A and C were treated with polyethylene glycol electrolyte powder for standard intestinal preparation, and those out of group B were given the above powder combined with Mosapride as enhanced intestinal preparation. The quality of intestinal preparation was evaluated by success rate of intestinal preparation, Boston intestinal preparation score (BBPS), polyp detection rate, time between intubation and extubation, and success rate of cecal intubation. The occurrence of adverse reactions, satisfaction with intestinal preparation and willingness to repeat intestinal preparation were recorded. SPSS statistics 19.0 was used for data analysis, and one-way ANOVA or Chi-square test was applied for intergroup comparison. Results Compared with group A, the success rates of intestinal preparation and cecal intubation, BBPS, and polyp detection rate were significantly higher, and the time between intubation and extubation was obviously shorter in groups B and C (all P< 0.05). The patients of group C had higher satisfaction level with intestinal preparation and willingness to repeat intestinal preparation scheme when compared with those of group A (all P<0.05). There were notable differences in the incidences of nausea and abdominal distention, satisfaction level with intestinal preparation and willingness to repeat intestinal preparation between groups A and B (all P<0.05). Conclusion BSFS has certain guidance value for the quality of intestinal preparation in elderly patients undergoing colonoscopy. Our intensive intestinal preparation scheme for the elderly with Bristol stool type 1 and type 2 has good effect and tolerance.