Breast milk diarrhea in infants is generally believed to be a lack of lactase in the body, lactase in breast milk can not be effectively digested, which leads to changes in osmolality and diarrhea. Treatment is as follows: 1, by supplementing lactase to reduce the symptoms, or oral antidiarrheal drugs, such as Simethicone, Mummy Love, Baoluoan and other drugs, these drugs have no side effects; 2, if the diarrhea is not obvious, 2-3 times a day or less, can be observed without treatment, can not be changed to lactose-free milk powder, such as the first meal of breast milk, the second meal to eat lactose-free milk powder; 3, if the symptoms are not serious, as far as possible, breast milk-based. If the symptoms are not serious, try to use breast milk as the mainstay and reduce the number of feedings of lactose-free milk powder. In conclusion, the principle of breastfeeding diarrhea is to breastfeed infants, especially small infants eat the most effective, nutrient-rich, most suitable for children’s bodies to absorb the intake of food is breast milk. Try to use breastmilk as the mainstay, and then switch to lactose-free milk powder when the symptoms are severe. If switching to lactose-free milk powder, try to use breastmilk as the mainstay, and the smaller the amount of lactose-free milk powder, the better.