This study attempted to examine the relationship between mother's psychological control, child's smartphone addiction, maladaptive cognitive emotion regulation strategy, and social anxiety, and to verify the sequential mediating effect of maladaptive cognitive emotion regulation strategy and social anxiety in the relationship between mother's psychological control and child's smartphone addiction. The subjects of the study were 376 high school students in the metropolitan area, and the study was conducted using the psychological control scale (PCS-YSR), the smartphone addiction scale (S-scale), the adaptive cognitive emotion regulation strategy scale (CERQ), and the social anxiety scale (SAS-A). For data analysis, descriptive statistics analysis, correlation analysis, mediating effect, and significance verification were conducted using SPSS 21.0 and PROCESS macro 3.5 programs. Summarizing the results of this study, first, mother's psychological control, smartphone addiction, maladaptive cognitive emotion regulation strategies, and social anxiety all showed positive correlation. Second, the mediating effect of social anxiety was significant in the effect of mother's psychological control on smartphone addiction, but the mediating effect of maladaptive cognitive emotional regulation strategy was not significant. Third, it was found that the sequential mediating effect of maladaptive cognitive emotional regulation strategies and social anxiety was significant in the effect of mother's psychological control on smartphone addiction.