Objective To explore the value of MRI in the diagnosis of shoulder joint injury. Methods The MRI data of 86 patients with shoulder joint injuries were collected and analyzed. Results The MRI detection rates of rotator cuff lesions, long tendon, shoulder instability and SLAP injury were 89.5% (34/38), 85.2% (22/27), 80% (8/10) and 63.7% (7/11), respectively. The sensitivity, positive predictive value and accuracy rate in the diagnosis of rotator cuff lesions were 93.9%, 96.9% and 91.8%, respectively, in the diagnosis of long tendon were 91.3%, 91.3% and 85.2%, respectively, in the diagnosis of shoulder instability were 85.7%, 75.0% and 70.0%, respectively, and in the diagnosis of SLAP injury were 75.0%, 85.7% and 72.7%, respectively. For patients with partial rotator cuff tears, high signal due to hematoma or hemorrhage in tendon can be observed on the MRI. Patients with long tendon of biceps muscle injuries showed tendon thickened and increased signal, subchondral osteosclerosis and subarticular capsule showing low signal. Conclusion MRI has a high detection rate for shoulder lesions. It can show the anatomical structure of shoulder joint in detail, with high sensitivity and accuracy in the diagnosis of soft tissue injury.