Objective: To explore relationship between Internet overuse tendency and academic achievement, mental problems and family function in middle school students. Methods: 2556 middle school students (1261 boys, 1295 girls, mean age, 15 + 2years) were divided into two groups; 361 students were with Internet Overuse Tendency (IOT group), 2195 students were control group. They were investigated and assessed by Family Assessment Device (FAD), Strengths and Difficulties Questionnaire for Parent (SDQ-P), and some questions designed by ourselves. Results: The prevalent rate of IOT among groups based on gender (2 = 86.6, P < 0.000), age (2 = 17.9, P < 0.01) and family training patterns (2 = 9.40, P < 0.01) were significant difference. Compared with control group, IOT group had lower academic achievements (2 = 30.1, P < 0.001), lower family function scores (t = 2.75-7.82, P < 0.01), more emotional and behavior difficulties scores and lower social behavior scores (t = 3.56-7.51, P < 0.001). Conclusion: In order to prevent and intervene IOT, we should pay more attention to not only solving emotional and behavior problems in middle school students, but also improving their family function.