Colonoscopy is a standard procedure for screening, monitoring, and treating colorectal lesions. To explore the impact of WeChat guidance on bowel preparation before colonoscopy. This quasi-experiment study included patients who underwent colonoscopy at Qingdao Endoscopy Center between March 2016 and September 2016. The primary outcome was bowel preparation quality (Ottawa score), the secondary outcomes were intubation time, withdrawal time, adenoma detection rate (ADR), and adverse reactions. Finally, 588 patients were included and divided into the WeChat guide (n = 295) and the non-WeChat guide (n = 293) groups, they were comparable in baseline characteristics. The Ottawa score (1.59 ± 1.07 vs. 6.62 ± 3.07, P < 0.001), intubation time (6.47 ± 1.81 vs. 11.61 ± 3.34, P < 0.001), withdrawal time (13.15 ± 3.93 vs. 14.99 ± 6.77, P < 0.001), and occurrence rate of adverse reactions (2.0% vs. 5.5%, P = 0.029) were significantly lower in the WeChat guide group than those in the non-WeChat guide group. ADR was significantly higher in the WeChat guide than that in the non-WeChat guide group (1.47 ± 2.30 vs. 0.84 ± 1.66, P < 0.001). WeChat guidance might improve the quality of bowel preparation and adenoma detection rate, shorten the time of colonoscopy, and reduce adverse reactions in bowel preparation.