Objective To explore application of MRI in preoperative diagnosis of pigmented villonodular synovitis (PVNS). Methods A retrospective analysis of clinical data was carried out in 50 PVNS patients treated in our hospital from March 2009 to October 2015 confirmed by operation and pathology, all patients underwent MRI and CT, preoperative MRI and CT imaging features of all patients were analyzed to estimate diagnostic value of MRI in preoperative PVNS. Results Detection rate of MRI to arthroedema, nodule and mass of soft tissue, synovial thickening, hemosiderosis were significantly higher than CT (P<0.05), 46 patients were diffuse type, 4 patients were topical type in 50 patients, hydrops articuli in different sizes could be seen, main behaviors were T1, T2 long signal, synovial membrane of articular capsule in different degrees uneven thickening could be seen in 46 patients in diffuse type, with soft tissue nodes in inequality of size, 2 cases of knee-joint and 2 cases of ankle joint were topical type, local single type circular and irregular nodules could be seen, thickened synovium and synovial nodule were low or equal signal in T1WI, most low high mixed signal were low signal in T2WI, synovium were uneven thickening, 18 cases of bursae suprapatellaris synovium edge were waved changes, nodositas and strip abnormal signal could be seen in 7 cases of infrapatellar capsula renis, high and low mixed signal could be seen in 5 cases of anterior and anterior cruciate ligament, arthrodial cartilage and cartilage destruction could be seen in 30 cases, main performances were defects and sunken in articular surface, signal in defect area was consistent with synovium, reactiveness edema signal could be seen in 46 cases of periarticular marrow, showed lamellar irregular T2 weighted high signal, 4 cases enhancement scanning prompted that thickened synovium and tuberculum were obvious strengthening. Conclusion MRI imaging features has characteristics in preoperative diagnosis of PVNS, MRI can be used as one important method to preoperative diagnosis of PVNS.