There are more reasons for sudden stomach pain at night, mainly including the following: 1. Gallstone disease: it can cause biliary colic, which is more likely to occur at night. The process of turning around during the patient’s sleep at night may lead to a change in the position of the stone in the gallbladder. If the stone is stuck in the position of the bile duct opening, it will lead to the inability to excrete bile, and biliary colic will occur due to violent contraction of the gallbladder. At this time, the patient will have severe pain, manifested as pain in the right upper abdomen and the right side of the back of the shoulder, and can go to the hospital for ultrasound, physical examination and blood tests to further clarify the diagnosis. 2. Urolithiasis: If the ureteral stone is stuck in the ureteral cross-vessel, i.e. the lower abdomen on both sides, it will also lead to sudden onset of abdominal pain, in most cases accompanied by radiating pain in the lower back and perineal area. Most of the patients will show hematuria in the naked eye or even positive percussion pain, which can be diagnosed by ultrasound and urine routine. 3, Gastrointestinal perforation: such as gastric diseases, patients may have a history of ulcer and sudden perforation of gastric ulcer at night, which leads to sudden total abdominal pain. 4, Associated diseases: such as small bowel diseases, patients suffering from small bowel diseases have relatively few cases of sudden pain at night, but the presence of abdominal pain may occur in cases of internal hernia or torsion and colon related diseases.