The sour odor of the child’s hair may be caused by physiological factors, but also may be related to seborrheic dermatitis, tinea capitis and other pathological factors. 1. Physiological factors: the baby usually exercise more, sweating more, if the baby is not cleaned, sweat constantly infiltrated, may form sour odor. It is recommended to pay attention to cleanliness and hygiene, regular cleaning for the baby, especially when sweating more, it is recommended to increase the frequency of cleaning, can help reduce the odor of sweat. 2. Pathologic factors: (1) seborrheic dermatitis: can occur in seborrheic parts, such as the head and face, often manifested as scalp erythema, covered with greasy scales, especially when the weather is hot, it is easy to cause hair sour odor. (2) ringworm: mostly caused by fungal infection, can also appear red spots, pimples, scales, etc., at the same time, yellow ringworm and other may produce obvious odor, resulting in baby hair, scalp sour smell. Parents are advised to bring their children with sour hair to regular hospitals for consultation and standardized treatment under the guidance of a doctor after a clear diagnosis, while patients usually pay attention to cleanliness and hygiene, avoid scratching the scalp and so on.