Babies can simply determine the type of fever through the symptoms of fever as well as routine blood tests, which are analyzed as follows: 1. Fever symptoms: if the baby is accompanied by cough, runny nose, sore throat and other adverse reactions during the fever, it may be the fever caused by respiratory diseases. If also accompanied by vomiting, diarrhea, nausea and other adverse reactions, it may be the digestive system caused by fever. 2. Routine blood test: the baby can go to the hospital for routine blood test, if it shows high white blood cells, mainly lymphocytes, CRP is normal or slightly high, it may be the fever caused by viral infection. If the white blood cells are elevated and dominated by neutrophils, and CRP is obviously elevated, the symptoms may be caused by bacterial infection. 3. Other special tests: Infections caused by special pathogens require special tests, such as Mycobacterium tuberculosis. Parents need to go to the hospital in time for relevant examinations when their babies have fever, and cooperate with doctors to actively carry out treatment.