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.

Inclusion Criteria:

• outpatients aged 18-80 years
• referred for routine diagnostic colonoscopy
• with access to the educational video themselves or through close family members living in the same household were eligible.

Exclusion Criteria:

1. pregnancy or breastfeeding
2. allergy to purgatives
3. suspected intestinal obstruction, stricture, or perforation
4. hemodynamic instability
5. impaired swallowing reflex or mental status
6. severely medical status, such as New York Heart Association grade III or grade IV congestive heart failure and severe renal failure
7. illiteracy
8. history of oesophagus、stomach 、duodenum、small intestine or colorectal surgery
9. participation declined.