Objective To study the clinical application of 3.0T high-resolution magnetic resonance imaging (MRI)in diagnosis of anal fistula. Methods 60 patients with anal fistula underwent 3.0T MRI scan before surgery. The MR sequences were evaluated for demonstration of anal fistula, intemal openings, external openings, abscess and types of anal fistula.The MRI findings were compared with surgical results. Results On MRI examinations, The high position anal fistula was found in 15 patients, 9 patients had complex anal fistula, 6patients had simple fistula. The low position anal fistula was found in 45 patients, 25 patients had complex anal fistula, 20 patients had simple fistula. And 97 fistulas, 18 branch of fistula, 72 intemal openings, 70 external openings, and 9 perianal abscesses were detected by MRI. The diagnostic accuracy of MRI for fistula was 95.1% (97/102), the positive rate for interna1 fistula was 94.7% (72/76), The site, number and perianal abscess of external fistula showed with MRI was the same with operation. Conclusion High-resolution 3.0T MRI may provide more comprehensive anatommic and pathology information for clinical treatment of anla fistula, has great significance to the clinical treatment.