This year, hand, foot and mouth disease is more aggressive, characterized by not only the number of morbidity, but also a significant increase in the number of seriously ill children than in previous years, severe hand, foot and mouth disease is harmful to children, critical cases can be life-threatening. For the treatment of seriously ill children, clinical experts have initially concluded a set of practical methods, which can greatly improve the success rate of critical children as long as they are found in time. Therefore, the correct identification of the “signal” of severe HFMD plays a decisive role in the treatment of children with severe HFMD. 1. Persistent high fever that does not subside. 2, poor mental health, vomiting, limb myoclonus, limb weakness, convulsions. 3, Increased respiration and heart rate in the presence of normal body temperature. 4. Cold sweating and poor peripheral circulation. Children with HFMD, especially those under 3 years old, with a disease duration of less than 5 days and with the above characteristics, may develop into serious cases in a short period of time, and should be sent to a designated hospital for treatment in a timely manner.