Frozen shoulder has many causes, the more common ones are improper treatment of trauma to the shoulder joint, improper posture of the shoulder joint and chronic strain, local cold of the shoulder joint, degenerative changes of the shoulder joint and other factors. 1. Improper treatment of trauma to shoulder joint: after trauma to shoulder joint, it leads to injury of tissues around shoulder joint, and improper treatment can lead to aseptic inflammatory reaction and adhesion of tissues in the damaged area, which will lead to the formation of periarthritis. 2. Improper posture of shoulder joint and chronic strain: if the patient’s shoulder joint is in an improper posture for a long time, or if the patient is engaged in weight-bearing or strenuous exercise for a long period of time, it can cause chronic strain of shoulder joint muscles and other tissues, and then inflammation and adhesion will occur. 3. Cold shoulder joint: when the shoulder joint is in a low-temperature environment, it can lead to the contraction of local blood vessels and muscle spasm, and if it is repeatedly exposed to cold, it can also lead to adhesion and aseptic inflammation in the soft tissues around the shoulder joint. 4. Degenerative changes of shoulder joint: with age, the function of muscles and other tissues in the shoulder joint degenerate, muscle and tendon symptoms of dehydration and adhesion, the ability to withstand external forces will gradually weaken, and injury and inflammation are more likely to occur in activities, which is the basic factor for the development of frozen shoulder. There are other causes of frozen shoulder, which require timely medical treatment and active diagnosis and treatment to avoid delaying the condition.