A person’s left upper abdominal pain may be caused by gastric ulcer, angina, splenomegaly and other factors. 1. Gastric ulcer: When the barrier function of gastric mucosa decreases, gastric ulcer may occur. The ulcer surface may cause pain when stimulated by stomach contents and hydrochloric acid. Since the stomach is located in the left upper abdomen, a person’s left upper abdominal pain may be caused by a gastric ulcer. 2. Angina pectoris: when angina pectoris attacks, coronary artery spasm may occur, which may cause local myocardial tissue ischemia and hypoxia, release some metabolites, which may radioactively cause the left epigastric pain. 3. Enlarged spleen: the spleen is located on the upper left side of the stomach and is divided into four parts of the abdomen, and the spleen is also an organ of the left upper abdomen. When the spleen is enlarged, it may irritate its own pericardium and cause pain, and the person’s left upper abdominal pain will appear. When the left upper abdominal pain occurs, you should consult a doctor in time, and complete gastroscopy, electrocardiogram, abdominal ultrasound and other examinations under the guidance of the doctor to clarify the cause of the disease and actively treat it.