Sour and smelly stools in one-year-old babies are usually considered to be related to sugar indigestion, which is produced by fermentation by intestinal bacteria. This condition is mostly seen in non-infectious diarrhea, including catching a cold, overheated weather or improper addition of complementary foods and sudden changes in the types of complementary foods. It is recommended to give your baby lactase or change to diarrhea milk powder, you can eat rice soup, thin point rice porridge, noodles, drink more water as appropriate, stop fish, meat, eggs, vegetables, fruits, give your baby lactase, probiotics plus digestive aids to observe the medicine. If the baby has a fever, no improvement after taking medication, mental state is not good, it is recommended to go to the pediatric internal medicine department for further consultation, the need for routine blood tests to rule out bacterial infections.