There are many causes of pain below the left rib cage, which can be divided into physiological and pathological causes. Physiological causes usually do not require treatment and can be treated by paying attention to rest. If it is caused by pathological reasons, it may be caused by trauma, neurological diseases, cardiovascular system diseases, digestive system diseases and respiratory system diseases, etc. It is suggested that patients should go to the hospital in time and have CT, ultrasound and other related examinations under the guidance of doctors to clarify the causes and then treat the cause. I. Physiological causes: no warm-up activities before exercise or large physical activity, after sudden exercise, may cause muscle strain and pain below the left rib cage. Usually no treatment is needed, and most of them can be relieved after rest. Second, the pathological reasons: 1, trauma: the left side of the rib cage at the muscle damage, abrasions, such as skin breaks, left rib fracture, etc., will appear painful feelings. If there is no wound, cold compresses can be applied first, and hot compresses after 24 hours, and bruises can be taken to activate blood circulation and remove blood stasis. If a wound appears, it should be disinfected first to avoid wound infection; 2. Neurological diseases: After being infected by varicella-zoster virus, damage to nerves can occur, such as herpes zoster, intercostal neuritis, etc., and knife-like pain can appear under the left rib cage. Treatment is mainly directed at the cause, and pain medication and nerve-nourishing drugs can be added, and in severe cases, closure therapy and surgery can be performed; 3. Cardiovascular system diseases: when the heart is ischemic and infarcted, patients will have pain behind the sternum and in the precordial area, and some of them will also radiate to the pain under the left rib cage, such as angina pectoris, myocardial infarction, organic heart lesions, etc. Patients may also present with chest tightness, dyspnea, and left shoulder pain. These diseases should be examined by electrocardiogram, cardiac ultrasound, coronary angiography, and markers of myocardial damage under the guidance of a doctor and according to the patient’s own condition. After diagnosis, lifestyle improvement, oral medications for lipid-lowering, blood pressure-lowering, vasodilating and anti-arrhythmic drugs, anticoagulation therapy for patients with thrombosis, and interventional therapy or surgery may be required for severe thrombosis. In addition, patients found cardiovascular disease should be treated as early as possible to avoid delayed aggravation; 4, digestive system diseases: when digestive system diseases occur, some patients will also have pain under the left rib cage, such as acute gastritis, gastric ulcer, pancreatitis, splenic abscess, spleen rupture and other diseases. When the condition is mild, it can usually be treated with acid suppressants and gastric mucosal protectors, such as pantoprazole, omeprazole, thioglycollate, etc. In case of infection, oral anti-inflammatory drugs, such as cephalosporin and metronidazole, are administered under the guidance of a doctor. When the condition is serious, such as bleeding leading to shock, you should go to the hospital as soon as possible to continue resuscitation treatment such as anti-shock; 5. Respiratory system diseases: When patients have pneumonia, left pleurisy, pneumothorax and other diseases, it will also cause pain below the left rib cage, and cough, cough, fever and other symptoms. According to the patient’s disease and clinical manifestations, treatment can be paired with cough and phlegm relieving and anti-inflammatory drugs, such as Ambroxol Hydrochloride and Cefixime. In case of tuberculous pleurisy, anti-tuberculosis treatment is also required, such as taking anti-tuberculosis drugs like isoniazid and rifampin as prescribed by the doctor. Patients with severe respiratory distress should seek medical attention and be given oxygen inhalation to relieve the discomfort.