OBJECTIVE: To evaluate the efficacy and safety of thread-dragging through fistula method in treating patients with simple anorectal fistula. METHODS: In this multi-centered, prospective, and randomized controlled clinical trial, 244 patients with simple low or high anorectal fistula were randomly divided into study group (with the method of thread-dragging through fistula) and control group (with the method of incision or thread-drawing). The healing time and curative rate of anorectal fistula, and the integral calculus of clinical symptom and life quality evaluations before and after treatment were all examined. The maximal anal canal squeeze pressure was measured to compare the therapeutic safety between these two groups. The health economical benefits were also assessed to determine which therapeutic method was more economical. RESULTS: The curative rate of simple low and high anorectal fistula were of no significant differences between the study group and the control group. The healing time of simple low anorectal fistula in the study group and the control group were (22.26+/-8.67) d and (31.41+/-11.39) d respectively, while the healing time of simple high anorectal fistula in the study group and the control group were (24.73+/-8.15) d and (32.20+/-12.60) d respectively, and there revealed significant differences between these two groups. Each integral calculus of clinical symptom evaluation in the study group was not obviously different from those in the control group besides the integral calculus of anal sphincter function. The integral calculus of life quality between the study group and the control group of simple low anorectal fistula had no significant differences. The integral calculus of anal sphincter function and confidence in treatment in the study group of high anorectal fistula were better than those in the control group. The hospitalization expense of the study group was remarkably lower than that of the control group. The maximal anal canal squeeze pressure in the study group after treatment was not reduced obviously as compared with that in the same group before treatment, while it was decreased significantly in the control group after treatment as compared with those in the same group before treatment and in the study group after treatment. CONCLUSION: The method of thread-dragging through fistula in treating simple low and high anorectal fistula can shorten the course of the disease, save the hospitalization expenses, improve the life quality of the patients, and protect the anal sphincter function.