Electronic product use among preschool children is gradually widespread. To explore whether and how electronic product use causes problem behaviours in preschool children, this study analyses the relationships between the degree of electronic product use, problem behaviours, and the roles of parenting styles and parent-child relationships in between using questionnaires to survey 582 parents of children aged 3-6-year-olds. Results: (1) There are significant correlations between the four; (2) the Parent-child relationship mediated the relationship between electronic product use and problem behaviours; (3) Parenting style moderated both the relationship between electronic use and problem behaviours as well as parent-child relationship and problem behaviours. Conclusion: Excessive electronic product use can lead to parent-child conflicts and problem behaviours, while highly positive parenting styles can buffer these influences. This study provides further insights into the negative effects of excessive electronic product use and the protective role of parental guidance.