There are many causes of dehydration in infants, such as high environmental temperature, diarrhea, vomiting, etc. To summarize the symptoms related to the degree of dehydration, mild symptoms are not obvious, and moderate to severe can appear more obvious skin mucous membrane changes, circulatory system symptoms, respiratory changes and so on. Mild dehydration in infants mainly refers to the lack of water accounted for 3%~5% of body weight, at this time the clinical symptoms are usually not obvious. When the water loss accounts for 5%~10% of body weight, moderate dehydration is reached, at this time, infants can appear skin and mucous membrane changes, including skin elasticity is slightly reduced, mucous membrane dryness, reduced tears, fontanel is slightly sunken, etc.; circulatory symptoms, such as increased heart rate, pulse rate is weakened, postural hypotension; respiratory changes, which is manifested as deepening of respiration, slightly accelerated; urine output is reduced, etc.. In severe dehydration, the water loss is more than 10% of body weight. At this time, infants may show skin and mucous membrane changes, including skin pattern, dry and inelastic skin, dry and cracked lips and mouth, sunken eye sockets, and cold limbs, etc.; circulatory symptoms, such as increased heart rate, weakened pulse, and lowered blood pressure; respiratory changes, such as deepened and accelerated respiration, and urination, and fuzzy consciousness. It is recommended that infants with corresponding manifestations should consult the doctor in time, and after the diagnosis is made, the cause of the disease should be clarified and rehydration and other treatments should be carried out.