Pain on the left side of the chest can be seen for the following reasons: First, diseases occurring in the heart, especially during the acute attack, there will be a crushing pain in the precordial region, which can also radiate to the back of the left shoulder, and is caused by coronary spasm or embolism, which should be related to the underlying disease, especially with hypertension, diabetes, external environmental factors, cold, mood swings and pain can also induce coronary spasm Therefore, acute myocardial ischemia can be induced, and nitrate drugs should be given in time, and thrombolytic therapy is needed if necessary. Second, there are also some patients are caused by chest wall diseases, common is the rib chondritis or chest wall soft tissue contusion, will be manifested as pain, can be treated with oral pain medication, the application of aminoglutethimide tablets. Third, some patients are caused by breast diseases, and patients with breast enlargement will also show painful swelling of the chest.