Abstract: Objective To investigate the condition of over-using electronic product of young school-age children and the influencing factors of prolonged screen time after school in Shenzhen, so as to provide evidence for intervention of children's electronic product use. Methods Cluster sampling method was used to investigate the use of electronic products among the second grader in 18 primary schools in a district of Shenzhen. Results 47.4% of children owned electronic products, 46.8% of children had regular contact with electronic products before the age of 5, 15.7% of children exceeded the recommended screen time of 2 hours per day on average, and 34.8% of children had screen time of more than 2 hours per day on weekends. The main purpose of using electronic products was to do online homework （60.5%）, followed by entertainment/chatting （15.0%）. Logistic regression analysis results showed that father's screen time >2 h/d （OR=1.874）, mother's screen time >2 h/d （OR=1.815） might be risk factors for boys' screen time timeout, but sufficient mother's company time （>2.0 h/d）（OR=0.360, 0.244） might be protective factors for boys. Father's screen time >2 h/d （OR=2.202） and mother's screen time>2 h/d （OR=2.119） might be the risk factors for girls' screen time timeout. Conclusion Electronic products are widely used by lower grade pupils in Shenzhen. Parents should pay more attention to reduce their own screen time and increase company time to promote the children's physical and mental health development.

Key words: Primary school students, Electronic product, Screen time, Risk factor, Family factors