Objective To evaluate the value of magnetic resonance (MR) plain scan in the diagnosis and classification of Anal Fistulas. Then try to conduct a joint typing for all cases. Methods Retrospective analysis the MR information of 25 patients，all of which were diagnosed as anal fistulas based on surgical pathology, including the number and location of the inner mouth, the main tube, branch, associated abscess of anal fistula, and the anal fistula type, and then compared with the results of the operation. Results ① The sensitivity of MR plain scan in the diagnosis of the inner mouth, the main tube, branch, abscess was 88.2%, 91.2%, 88.9% and 100% respectively, the accuracy was 83.3%, 91.2%, 92.3% and 100% respectively, the positive predictive values was 96.8% and 100%, 88.9%, 100% respectively. ② The true positive cases of MR diagnosis were classified by two methods and compared with the surgical typing. The compliance rate of Parks was 100%, and the coincidence rate of MR was 87.0%. The two types can be combined. Conclusion ① 1.5T MR plain scan can accurately diagnose the inner mouth, the main tube, branch and associated abscess of anal fistula. ② MR plain scan can be used for accurate classification of anal fistula in two ways. The combination of the two types is complementary to each other, taking into account the anatomical details and the overall characteristics of the lesion, so joint typing has a guiding significance to the anal fistula surgery.