If the infant stool has black residue, mainly due to the addition of complementary food after the intake of blood products, suffering from gastrointestinal bleeding caused by the following: 1, after the addition of complementary food intake of blood products: more than 6 months later, you can gradually add complementary food, if you eat duck blood, pig blood, it will cause the stool into black, in this case, stop adding blood products to complementary food, the stool black will gradually disappear; 2, suffering from Gastrointestinal bleeding: bleeding in the digestive tract, will also cause black stools, this situation should be done in a timely manner the corresponding examination, such as colonoscopy, and gastroscopy, etc., in a timely manner to find the causes of gastrointestinal bleeding, so as to carry out targeted treatment, otherwise it will cause hemorrhagic anemia and shock, etc.