Abstract: Objective To study the prevalence of internet addiction diso rder(IAD)and the influencing factors among the students in Heilongjiang province and to provide bases for the intervention measures.Methods A stratified randomcluster sample of 10800 students in 29 schools from Harbin,Jiamusi,Suihua cities was investigated with an anony mous question naire.Results The prevalence of using internet was 54.66% with 8.38% of internet addictio n disorder,19.33% of video game addiction and 13.89% of gambling.Multivariate logistic analysis indicated that gender,loneliness,video game,suicided,preparing to suicide,idea of suicide,g ambling have positive correlation with IA D,the specific ORs are 1.948,1.592,2.979,2.325,2.324,1.497,respectively.Conclusion IA Damong adolescent in mo derate cities ar e higher than other cities of Heilongjiang province.IAD correlated with the factors such as gender,loneliness,suicidal ideation,gambling.