Pain appears in the lower left corner of the stomach, firstly, it should be gastrointestinal cause, it may be caused by acute gastroenteritis, intestinal spasm or intestinal dysfunction. Secondly, it may be ureteral diseases, such as ureteral stones or urinary tract infections. If it is ureteral stones, the pain usually comes out of nowhere, and the pain is more intense, and in severe cases, it may even appear pale, cold sweat, vomiting and so on. If it is an infection of the ureter and the urinary tract, in addition to localized pain, there will be frequent urination, urinary urgency and painful urination. Third, if it is a woman, it must be considered whether there are gynecological problems, such as ectopic pregnancy, ovarian cyst tip torsion or ovarian corpus luteum rupture and other symptoms. In addition, acute or chronic pelvic inflammatory disease may also present with left lower abdominal pain.