Abstract: Objective To explore the relationship between online time and sub-health among adolescents.Methods A total of 2137 students in their first or second year of study were recruited from two junior and two senior high schools and two universities in urban and rural areas of Ji'nan city and surveyed with Multidimensional Sub-Health Questionnaire of Adolescents(MSQA) and the revised Internet Addiction Diagnostic Questionnaire designed by Young.Results The prevalence of overall sub-health was 3.04%(65/2137).Logistic regression analyses showed that internet use time(odds ratioOR=20.950,95% confidence interval95%CI:5.499-79.818) was a risk for overall sub-health among the adolescents.The students with frequent internet use had significantly higher numbers(17.33±3.89) of sub-health symptoms compared to the students with general internet use(15.09±3.24) and less internet use(11.55±1.11)(both P<0.05).Pearson correlation analysis showed that internet use time was positively correlated with total score of sub-health(r=0.405,P<0.001).Conclusion Internet use time correlates with physical and psychological sub-health and problematic internet use is a risk factor for healthy development among adolescents.