Black stool with hidden pain in the abdomen consider gastroenteritis, gastrointestinal tumor, upper gastrointestinal bleeding and other conditions. 1. Gastroenteritis: when the inflammation of gastrointestinal tract stimulates the intestinal wall of the patient, hidden pain in the abdomen will appear, and when the small blood vessels in the intestines are dilated, the feces will have occult blood and show black color. 2. Gastrointestinal tumor: when the patient has gastrointestinal tumor, due to the tumor stimulation of the surrounding tissues, there will be hidden pain in the abdomen, and the tumor itself bleeds or causes the bleeding of the surrounding organs, which will cause the black stool. 3. Upper gastrointestinal bleeding: when patients suffer from upper gastrointestinal bleeding due to upper gastrointestinal ulcer or severe gastritis, when blood flows into the intestinal tract, it will cause black stool and hidden pain in the abdomen. In addition, there may be other causes of black stool and abdominal pain, it is recommended that patients go to the hospital in a timely manner, improve the examination to determine the cause of the disease, and then give targeted treatment or treatment under the guidance of the doctor.