The left side of the rib cage pain should be considered skeletal disease, cardiovascular disease, neurological disease, etc.. 1. Skeletal system diseases: such as rib trauma, the patient will have a history of trauma such as collision before the pain. 2. Cardiovascular diseases: mainly seen in coronary atherosclerotic heart disease, patients because of insufficient blood supply of coronary blood vessels, after strenuous activities or cold and other factors, there will be left anterior chest discomfort or hidden pain, severe cases will appear anterior chest pain. 3. Neurological diseases: mainly seen in intercostal neuritis, patients may experience pain distributed along the intercostal space. There may be other reasons for the vague pain at the left side of the ribs, which should be promptly consulted and actively treated.