The present study explored the effect of parent-child relationship on Smartphone Use Disorder (SUD) and the mediating role of quality of life (QOL). In addition, we explored the role of educational level from the developmental psychology perspective. Our results indicate that: (1) parent-child relationship could negatively predict SUD among adolescents; (2) QOL played a partial mediator role in the relationship between parent-child relationship and SUD; (3) As educational level increased from elementary school to middle school to high school, the effect of parent-child relationship on QOL weakened. This study showed that adolescents with good parent-child relationship had a higher QOL thus exhibiting a lower extent of SUD. Moreover, the link between parent-child relationship and SUD weakened as the educational level increased.