This is a multicenter clinical trial investigating the safety and efficacy of inhaled Peginterferon α-2b at different doses, in combination with supportive care, for the treatment of patients with hand, foot, and mouth disease (HFMD) of ordinary type. The trial aims to enroll 90 patients with HFMD. Eligible subjects will be randomly assigned to receive either supportive care + Peginterferon α-2b mcg or supportive care + Peginterferon α-2b 90 mcg, administered on days 1 and 3. The study period includes a 3-day screening phase and a 5-7 day inpatient visit period. The results of this trial will be used to evaluate safety and efficacy.