Pain at the joint of arm and shoulder, i.e. shoulder joint pain, may be caused by physiological factors such as overwork, or pathological factors such as trauma, frozen shoulder and shoulder joint lesion. 1. Physiological reasons: it is mostly seen in long-time physical labor, which makes the local overwork, leading to the accumulation of lactic acid and other metabolites in the soft tissues around the shoulder joint, thus causing pain in the joint between the arm and the shoulder. 2. Trauma: It is common in patients with fracture of shoulder joint, rotator cuff injury, muscle and nerve injury caused by trauma, which may cause pain in the joint of arm and shoulder. 3. Frozen shoulder: long-term strain on the shoulder joint can cause damage to the joint capsule, fascia, ligaments and other tissues, resulting in aseptic inflammation of the surrounding tissues and stimulation of the peripheral nerve endings, and the patient may experience pain at the joint of the arm and shoulder. 4. Shoulder joint lesions: such as shoulder joint infections, tumors and other diseases, compression or stimulation of the surrounding tissues, patients may experience pain in the joint of the arm and shoulder. There may be other reasons for pain in the joint of arm and shoulder, it is recommended to consult a doctor in time to clarify the cause of the disease and carry out targeted treatment.