Pain in the lower corner of the left belly generally refers to left lower abdominal pain, which may be caused by left ureteral stone, proctitis, intestinal obstruction, etc. If the patient is a woman, it may also be caused by the left adnexitis, etc. 1. Left ureteral stone: Ureteral stone is usually caused by urinary tract obstruction, metabolic abnormality, low water intake, etc., and the patient will have severe pain in the abdomen, accompanied by hematuria, dysuria or anuria and other symptoms. 2. Proctitis: proctitis is usually caused by infection, foreign body damage, etc., the patient’s left side of the abdomen will have pain, the patient’s anus will also have severe pain, and accompanied by constipation, fever, weight loss, loss of appetite and other symptoms. 3. Intestinal obstruction: Intestinal obstruction is usually caused by intestinal torsion, intra-abdominal abscess and other reasons, the patient’s abdominal pain is usually persistent and intensified pain, accompanied by vomiting, abdominal distension, anus stop defecation and other symptoms. 4. Left-sided adnexitis: when the left adnexa of female patients are stimulated by inflammation, the patient’s left lower abdomen will appear pain, in activities or after sexual intercourse will be aggravated, and accompanied by menstrual abnormalities, vaginal discharge increase and other symptoms, the condition is more serious, there may also be high fever, headache, chills and other systemic symptoms. There are many other reasons for the symptoms of lower left abdominal pain, you should go to the hospital in a timely manner to consult a doctor, after diagnosis and treatment as prescribed by the doctor.