The judgment of the severity of rotator cuff injury is mainly based on the severity of the patient’s symptoms (pain, etc.), physical examination and relevant auxiliary examinations (MRI, etc.). 1. Symptoms: If the pain is mild and there is no obvious movement of the shoulder joint, the rotator cuff injury is considered to be mild; if the pain is more severe, especially when the movement of the shoulder joint is limited due to pain, the injury is considered to be more serious. 2. Physical examination: the examination of the affected area reveals that there is limited pressure and pain in the shoulder joint, and the shoulder drop test and impingement test are negative or insignificant, which indicates that the rotator cuff injury is mild; if the range of pain is more extensive, the pressure and pain is intense, and the shoulder drop test and impingement test are obviously positive, which indicates that the injury is serious. 3. Auxiliary examination: commonly used MRI examination of the shoulder, mild rotator cuff injury only exists in mild hemorrhage and edema, while severe injury shows partial or total tearing of the rotator cuff. Patients with rotator cuff injury are recommended to seek medical treatment in time, complete all the examinations in order to clarify the condition, and then be treated by professional doctors accordingly.