The reasons why a patient’s shoulder does not hurt during the day but hurts at night are as follows: First, rotator cuff injury: The typical feature of rotator cuff injury is pain in the shoulder joint at night, often accompanied by limited supination and weakness of supination of the shoulder joint. The rotator cuff is the power muscle of the shoulder joint from 60-120 degrees of abduction. If there is an injury or tear in the rotator cuff, there will be a decrease in the abduction and supination power of the shoulder joint, as well as a functional limitation. At night, especially when the patient is in a quiet state, the pain at the shoulder will be felt to increase. Secondly, malignant tumor of shoulder joint: especially osteosarcoma or giant cell tumor of bone in the proximal humerus, malignant tumor is characterized by significant pain at night, and X-ray and nuclear MRI examination should be performed to make a comprehensive judgment.