Oppositional Defiant Disorder (ODD) is a developmental disorder characterized by serious and persistent social impairment, especially stressful interactions with parents. Although previous studies demonstrated associations between parent mental health and children's ODD symptoms, less attention has been paid to integrating both parent and child risk factors. The purpose of the current study was to investigate the associations among parent emotion regulation, child emotion regulation, parental depression, and child depression in Chinese children with ODD. A total of 234 children with ODD ranging in age from 6 to 13 years, along with their fathers or mothers, completed questionnaires. Results indicated that: (1) Parent emotion regulation, parental depression and child emotion regulation were significantly correlated with children's depressive symptoms. (2) Parent emotion regulation was related to children's depression indirectly through parental depression and child emotion regulation. (3) Child emotion regulation fully mediated the relationship between parent emotion regulation and child depression, and also fully mediated the relationship between parental and child depression. These findings highlight the need to improve parent emotion regulation and pay attention to parental mental health, because both risk factors may exacerbate their children's emotion regulation difficulties and further associate the high level of depressive symptoms among children with ODD.