Abstract: Objective To appraise the clinical efficacy of colon hydrotherapy and drug therapy in treatment of slow transit constipation (STC) patients. Methods 146 STC patients were randomized into two groups. Colon hydrotherapy was used to treat 70 STC patients four to six times and drug therapy to treat 76 STC patients for four weeks. Then the clinical efficacy, days of continuous improvement and changes of colon motility were analyzed. Results The general improvement rate in STC patients was 92.8% in the colon hydrotherapy group and 92.1% in the drug therapy group (P>0.05). The duration of constipation improvement in the colon hydrotherapy group was much longer than that in the drug therapy group (P<0.01), and the degree of colon motility improvement in the colon hydrotherapy group was higher than that in the drug therapy group (P<0.01). Conclusions The colon hydrotherapy hydrotherapy is a good method to improve colon motility of STC and can effectively improve STC.