Objectives: This study analyzed the relationship between mothers’ emotional expressiveness, young children’s self-regulation ability, and smart device overdependence tendency. In addition, it examined the direct and indirect effects of mothers’ emotional expressiveness and young children’s selfregulation ability on the smart devices overdependence tendency through structural model analysis. Methods: Participants in this study consisted of 225 young children and their mothers living in G city. Data were analyzed using SPSS ver. 18.0 and AMOS ver. 18.0 to carry out descriptive statistics, correlation analysis, and the structural equation model. Results: The findings reveal that self-regulation ability negatively correlates with smart devices overdependence tendency. Moreover, the mother’s positive and negative emotional expressiveness indirectly affected the young children’s smart devices overdependence tendency through selfregulation. In other words, it was found that the mother’s emotional expressiveness completely mediates the young children’s self-regulation ability and indirectly affects the smart device overdependence tendency. Conclusion: The significance of this study is that it revealed risk and protective factors that affect young children’s smart device overdependence in a social situation where the problem of young children’s smart device overdependence has become more serious. Essentially, the findings can be utilized to develop a smart device overdependence prevention program for young children.