Pain on the left side of the stomach is mainly considered to be caused by digestive system diseases, or lesions in other parts of the body, and patients need to go to the hospital for examination to clarify the causes and then targeted treatment. Common causes and treatment 1, digestive system diseases: most of the pain on the left side of the stomach is caused by stomach diseases, such as gastritis, reflux esophagitis, gastric ulcer, etc., which may have a past history of chronic gastric disease, induced by poor dietary habits in daily life. The condition needs to be judged according to the individual’s clinical symptoms, combined with ultrasound, abdominal CT and other imaging examinations, and if necessary, gastroenteroscopy. Treatment can be under the guidance of doctors, the application of drugs such as domperidone tablets, omeprazole, gastric pellets, while a light diet and attention to rest; 2, other system diseases: if the left side of the stomach pain situation excludes digestive system diseases, further consideration needs to be given to lesions caused by other parts of the body, such as common pleurisy, intercostal neuritis, chondromalacia, and a small number of patients with myocardial infarction may also have pain on the left side of the stomach. It is recommended to visit the corresponding department for further improvement of chest CT examination and, if necessary, anti-inflammatory and pain-relieving medication. In the case of elderly people with a previous history of coronary heart disease and episodes with chest tightness, shortness of breath and other uncomfortable symptoms, an ambulatory electrocardiogram needs to be improved to exclude the possibility of heart attack.