Left-sided chest pain can be seen for the following reasons: first, previous history of intrapulmonary infection, residual pleural thickening, or acute stage of intrapulmonary infection pleurisy, there will be pins and needles pain in the chest, accompanied by limitation of deep breathing. Chest CT examination can be found in the lung tissue patchy image, there will even be a small amount of exudation, should be actively anti-infection treatment. Secondly, patients with myocardial ischemia, especially middle-aged and elderly patients are more common. After exertion, emotional excitement, will trigger the emergence of symptoms, electrocardiography can have obvious ST segment changes, timely oral nitrate drugs, the patient’s symptoms can gradually improve. Thirdly, for patients with breast hyperplasia, it will also be manifested as breast pain on the left side of the chest, and the pain has a certain regularity, in the pre-menstrual period, the symptoms are obvious, and the pain gradually reduces or even disappears after the menstrual period, and the patients with breast hyperplasia will also be manifested as a lump in the mammary glands, which is usually related to the increase of estrogen.