Left side subcostal pain, accompanied by pain when breathing.1. Consider respiratory diseases, such as pneumonia involving the pleura, or acute pleurisy will appear in the left side of the rib pain, pain will be aggravated by breathing.2. See the lung occupational disease, especially lung malignant tumors often appear in the subcostal pain, pain will be aggravated by breathing, and the main suggestion is that the patient go to the hospital and take a CT of the lungs for a clear diagnosis, in order to identify the pneumonia, pleurisy or pulmonary occupational disease, and give symptomatic treatment.3. Some patients, such as coronary heart disease, angina, may also have pain under the left rib, accompanied with pain when breathing. It is mainly recommended that the patient go to the hospital to take a lung CT to make a clear diagnosis, in order to identify the pneumonia, pleurisy or lung space-occupying disease, and to give symptomatic treatment.3. Some patients, such as coronary heart disease and angina pectoris, may also have left subcostal pain, which may be aggravated by the pain when breathing. At this time, we should consider giving the patient to check the electrocardiogram, if necessary, do coronary angiography to clarify the diagnosis.