Inclusion Criteria:  Participants who were scheduled for colonoscopy age between 18 and 80 years  Exclusion Criteria:  uncontrolled acute or recurrent chronic intestinal infections active gastrointestinal bleeding, gastrointestinal stricture, intestinal obstruction severe electrolyte metabolism disorder, severe coronary heart disease, heart failure, renal failure or liver failure pregnant, lactating, have metal diseases or refuse to colonoscopy examination