Objective: To observe the application effect of sodium phosphate powder in bowel preparation for colonoscopy in the elderly. Methods: Sixty elderly patients who underwent elective colonoscopy in the Shangrao People"s Hospital from October 2024 to January 2025 were selected as the research subjects. According to random number table method, they were divided into the control group (30 cases taking polyethylene glycol electrolyte powder) and the observation group (30 cases taking sodium phosphate powder). The effect of bowel preparation [Boston Bowel Preparation Scale (BBPS)], tolerance and compliance were compared between the groups. Results: BBPS scores of the right colon, transverse colon and left colon, tolerance rate and compliance with re-administration of laxatives in the observation group were higher than those in the control group (P<0.05). Conclusion: For the elderly, taking sodium phosphate powder for intestinal preparation before colonoscopy can improve intestinal cleanliness. Besides, they are highly tolerant to the powder and compliant with re-administration.