Shoulder pain can be caused by diseases of the shoulder joint itself, such as inflammation of the shoulder joint, including inflammation with bacterial infection and inflammation without bacterial infection, and bacterial infection is divided into specific infection and non-specific infection. Aseptic inflammation is more diverse and includes arthritis, rheumatoid arthritis, osteoarthritis, allergic arthritis, gouty arthritis, ankylosing spondylitis, etc. Injuries are the most common cause of shoulder pain. Injuries can be violent injuries caused by a definite violent action, violent injuries can lead to bony injuries of the shoulder joint, i.e. fractures, while more common are soft tissue injuries inside and outside the shoulder joint, such as: joint capsule, ligaments, tendons, muscles, glenoid lips, cartilage injuries, etc. The cause of shoulder joint pain can also be shoulder joint tumors, which include benign tumors, malignant tumors and metastatic tumors. Sometimes shoulder pain is not always due to the shoulder joint itself. Disorders of the neck, such as cervical spondylosis, which is the most common, can cause shoulder pain. Heart conditions such as myocardial infarction and angina can sometimes radiate to the left shoulder and be misdiagnosed as frozen shoulder. Gallbladder disease, gallstones, and cholecystitis pain radiating to the right shoulder can also be mistaken for frozen shoulder. In conclusion, there are many diseases that can cause shoulder pain, so shoulder pain should be carefully diagnosed, the cause should be clearly identified, and the treatment should be tailored to the symptoms.