Pain on the left side of the navel may be caused by pancreatitis, proctitis, left ureteral stone and other diseases. 1. Pancreatitis: Pancreatitis is an inflammatory reaction of the pancreatic tissue, which may be caused by biliary tract infection, pancreatic duct stones, abdominal surgery, metabolic disorders, etc. Pancreatitis can lead to impaired pancreatic function, which results in the symptom of pain on the left side of the navel. 2. Proctitis: Proctitis is mostly caused by pathogenic infections, such as bacteria, viruses, protozoa, etc. It can also be caused by overwork, mental stress, abuse of antibiotics and other factors, the patient will have the symptoms of pain in the left side of the navel, but also may have anal drop feeling, diarrhea and other symptoms. 3. Left ureteral stone: left ureteral stone may be left kidney stone discharge process stays in the ureter caused by metabolic abnormalities, urinary tract obstruction, infection and other factors related to the patient will appear left renal colic symptoms, manifested as pain in the left side of the stomach. There are more causes of pain on the left side of the belly button, and when the patient has a pain attack, it is recommended to be admitted to the hospital for examination and to cooperate with the doctor for treatment.