The left back pain can be caused by the following reasons: First, heart disease, when the heart has a heart attack or angina pectoris, can be radioactive pain at the left back scapula, can be accompanied by discomfort in the precordial area, this time to check the heart ultrasound, electrocardiogram and imaging to diagnose and early treatment. Second, herpes zoster, in the early stage of herpes zoster, there can be tingling or hidden pain on one side of the back, and after 1-2 weeks of incubation period, there can be clusters of herpes, then it is necessary to go to the dermatology department for early diagnosis and early treatment. Third, intercostal neuralgia, patients with intercostal neuralgia can have hidden pain, stabbing pain or radiating pain at the intercostal nerve on one side of the back, which should be investigated early and treated with nerve nutrition and closure therapy early after diagnosis. Fourth, lung diseases, when there is a tumor in the lung or a tumor in the pleura of the chest cavity, there can also be pain on one side of the back, then the CT of the lung should be examined to diagnose.