Frozen shoulder is a chronic inflammatory disease that causes pain and impaired movement in the shoulder joint. It is generally believed that frozen shoulder occurs on the basis of soft tissue degeneration around the shoulder joint. Many chronic injuries involve the joint capsule and surrounding muscles, tendons, and bursae, resulting in a non-specific inflammatory response that causes muscle spasm around the shoulder joint, leading to impaired movement. The pathological process of frozen shoulder can be divided into: painful phase, stiffness phase, and recovery phase. In terms of treatment, my experience is to reduce extensive shoulder exercises, keep warm and do some massage or physical therapy. The more you exercise in a wide range of motion, the more damage to the shoulder joint and the more painful it is. However, it is important to note that shoulder pain is not necessarily frozen shoulder. The author has found several cases each year in the clinic where shoulder pain is seen as frozen shoulder, but the test result is a terrible cancer. Due to the physiological structure, cancer in the lung tip can compress the nerve under the clavicle or cause pain in the shoulder, the inner part of the upper limb and the back of the shoulder due to involvement pain, which can be mistaken for frozen shoulder and taken lightly. By the time the symptoms become obvious, it is already in advanced stage and cannot be treated. Besides, lung cancer also occurs in people around 50 years old. It is not difficult to distinguish between the two. Frozen shoulder is caused by aseptic inflammation and spasm of the surrounding muscles, which is mainly manifested as shoulder joint dysfunction with pain. In contrast, patients with lung cancer are mainly painful, but shoulder joint dysfunction may or may not be obvious, and it is easier to distinguish between them by asking about their medical history, as they both have symptoms of coughing and coughing up sputum, as well as some examinations by doctors.