Objective: The present study investigated the prevalence of Internet addiction in Shenzhen adolescents and its predicative factors, so as to provide a reference for precisely identifying the adolescents of internet addiction and conducting intervention. Methods: Cluster random sampling method was applied to select the middle school students of grade 1 in 5 middles schools in Shenzhen. Three waves of data were collected over 3 years from students in 5 secondary schools in Shenzhen. Young s 10 item Internet Addiction Test, Chinese Positive Youth Development Scale, Chinese Family Assessment Instrument, Academic Maladaptation Scale and Demographic Variables Questionnaire were used, and finally the data of 1 301 students was proved to be valid. Results: The adolescents met the criterion of Internet addiction were 14.4%, 15.5% and 14.7% over past three years. The incidence of Internet addiction was stable among teenagers during the three years( F =2.53, P =0.08); The multivariate linear regression analysis showed that positive youth development, good family functioning indicators and academic maladaptation could predict the higher probability of having Internet addiction( P <0.05). Conclusion The phenomenon of Internet addiction among teenagers in Shenzhen junior middle school is common and relatively stable. The teenagers from the family of positive function, with positive development and with less academic maladaptation are less likely to suffer from internet addiction.