High quality bowel preparation is essential for successful colonoscopy. This study aimed to assess the impact of reinforced education by Video on the quality of bowel preparation. This prospective, endoscopist-blinded, randomized, controlled study was conducted. Reinforced education groups received additional education via reminders by video 2 days before colonoscopy. The primary outcome was the quality of the bowel preparation according to the Boston Bowel Preparation Scale (BBPS). The secondary outcomes included polyp detection rate (PDR), adenoma detection rate (ADR), tolerance, and subjective feelings of patients.