Abstract: Parents play a critical role in influencing physical activity (PA) levels of children and adolescents. Thus, systematic studies on the intergenerational transmission of PA between parents and children needs to be strengthened. Based on a nationwide survey of 126 817 parent-child pairs, this study revealed significant intergenerational transmission of PA, and the effect strength exhibiting heterogeneity across parent-child combinations, children’s educational stages, and socioeconomic levels. Further analysis indicated that parental support levels moderated the transmission of PA between parents and children. The challenges of intergenerational transmission of PA can be summarized in four main aspects: the insufficient PA of parents exacerbating the negative transmission trend, gender roles and academic pressure leading to differentiated transmission pathways, the entrenchment of intergenerational transmission models in low socioeconomic status families, and weak parental support leading to insufficient transmission motivation. To address the above mentioned challenges, this study proposes the following strategies: enhancing parents’ systematic understanding of PA and setting an example by parents through active participation; raising women’s awareness of active participation, and establishing communication and cooperation between family and school; optimizing the allocation of parent-child sports resources and promoting the sharing of community sports resources; creating joint participation activities for parents and children and incorporating support to enhance transmission motivation.