The baby’s fever but good spirits, may be related to physiological factors, belonging to the transient fever; may also be caused by pathological factors, in addition to fever is not too much to affect the baby’s mental state. 1. Physiological factors: the baby after a full meal, crying, keep warm excessively, may make the baby’s body temperature mildly increased. If the baby’s spirit, diet are normal, after loosening the clothes or quiet measurement of body temperature is normal, no other symptoms, can first be observed, no special treatment. 2. Pathological factors: infants and young children some of the early stage of the disease is often manifested as fever, but generally more manifested as a high fever, other symptoms are not obvious, such as toddler rash, Kawasaki disease, etc., at this time should be timely access to medical care, to further clarify the cause of the disease. In short, the baby if once in a while the temperature is slightly higher than normal, may be physiological conditions, can be repeatedly measured, if the performance of medium-high fever or repeated low fever, should promptly seek medical attention, to clarify the cause of the disease, to avoid delaying the condition.