ObjectivesThe purpose of this study was to explore the impact of the COVID-19 outbreak on children’s behavior and their parents’ mental health in China. MethodsA total of 30861 children’s parents were selected from throughout China to complete the self-made Child behavior Questionnaire and Child Parents Mental Health Questionnaire. ResultsThe results showed that there were significant differences in children’s behavior scores in variables such as age, whether or not an only child and place of residence; There were significant differences in physical, emotional and cognitive scores of parents in variables such as gender, age, education, occupation, place of residence, whether there are medical staff in family, the relationship with children, and children’s age. The correlation analysis showed that children’s behavior and parents’ physical, emotion and cognition were significantly correlated with epidemic-related factors. The stepwise multiple linear regression analysis showed that epidemic-related factors can significantly predict children’s behavior and parents’ physical, emotion, and cognition. ConclusionsThese results can provide theoretical basis for the behavior management of children at home and the psychological adjustment of parents during the epidemic.