Objective To compare the diagnostic value of shoulder joint arthrography with MRI and MR in patients with rotator cuff injury. Methods 106 cases of patients with suspected rotator cuff injury admitted into the hospital during July 2013 to December 2014 were studied and all of them received MRI examination. Then, there were 55 cases receiving arthrography with MR and 20 of whom were highly suspected cases and received arthroscopic diagnosis and treatment to make a definite diagnosis. The diagnostic accuracy of MRI and MR was compared. Results Among 20 cases of patients examined by arthroscopy, there were 12 cases diagnosed as having partial-thickness rotator cuff tears, 5 cases as full-thickness rotator cuff tears and 3 cases as rotator cuff degeneration, including 6 cases as rotator cuff tear concurrent glenoid labrum injury. The accuracy of MRI diagnosis was 55.0% (11/20) which was significantly lower than 100.0% (20/20) of Mrar and the comparison was statistically significant (χ2 =11.613, P=0.000＜0.05). Conclusion Although both of MRI and MRar can not well show the status of rotator cuff calcification, the application of MRar in the clinical diagnosis of rotator cuff injury is of higher accuracy, which can be used as the first diagnostic method.