One side of the stomach pain may be caused by the following aspects: 1, gastrointestinal diseases, such as acute or chronic gastroenteritis, intestinal colic, gastrointestinal tract dysfunction, or local intestinal polyps and tumors, there may be localized pain. 2, urinary system diseases, commonly urinary stones or urinary tract infections. If the urinary stone, in addition to one side of the abdominal pain will also lead to the same side of the renal region of the percussion pain or accompanied by the formation of blood in the urine. If it is a urinary tract infection, in addition to abdominal pain, but also manifested in the frequency of urination, urinary urgency, urinary pain, fever and other symptoms.3, if a woman may have gynecological diseases, such as acute or chronic pelvic inflammatory disease, dysmenorrhea, endometriosis, ovarian cysts, torsion, or even the rupture of an ectopic pregnancy bleeding, there will be a side of the abdominal pain, the main location of pain is the main pain in the lower abdomen.