Previous studies have emphasized the effect of parent marital conflict on youth's Internet addiction. However, few researchers have examined the mediating role of parent-child attachment and peer attachment between marital conflict and Internet addiction. To fill in this gap, this study aims to examine whether father-child, mother-child, and peer attachment play a mediating role between parent marital conflict and Internet addiction. This cross-sectional study included 450 college students in two Universities in China. Structural equation modeling (SEM) was conducted to examine research questions. Results showed that Internet addiction was positively associated with marital conflict and negatively associated with peer attachment. Moreover, both mother-child and father-child attachment mediated the relationship between marital conflict and Internet addiction through peer attachment. To our knowledge, this was the first study examining the mediating role of parent-child and peer attachment between parent marital conflict and youth's Internet addiction. Our findings suggested that educational workers should pay more attention on the development of youth's parent-child and their peer attachment, because youth's attachment played an important role in youth's Internet addiction. Moreover, our findings emphasized that father and mother both important people on the development of youth's peer attachment, which may in turn influence youth's Internet addition. •Parent marital conflict has a direct effect on youths' Internet addiction.•Father-child, mother-child and peer attachment were all important mediators.•Clinicians should pay more attention on youth's attachment development.•Both father and mother were important people in youth attachment development.