The prevalence of asthma in children has increased significantly, and the onset age is becoming younger.An early diagnosis of asthma in young children under 5 years of age, and early effective interventions are necessary.The diagnosis criteria of asthma in children under 5 years old at home and abroad have been revised, and multiple asthma prediction tools have been applied to the early diagnosis.However, a consensus on the diagnosis of asthma in high-risk children under 5 years of age still lacks.This study aims to review the domestic and foreign diagnostic criteria of asthma in children under 5 years of age and research progress of asthma prediction tools, aiming to improve the early identification and early diagnosis of childhood asthma by pediatricians, so as to carry out early interventions and achieve a good control.