Objective To explore the medium effect of social support in process of attachment styles and coping styles on criminal juveniles and adolescents with mood disorders.Methods The survey used in the research included Experiences of Close Relationships Inventory (ECR),Social Support Revalued Scale(SSRS) and Coping Style Questionnaire(CSQ) conducted by three groups:177 criminal juveniles,80 adolescents with mood disorders and 163 normal teenagers.Results Firstly,there were significant differences in the avoidant attachment,attachment anxiety,objective support,subjective support,utilization of support,solving problem,rationalization,self-accusation and retreat among three groups (F=7.902,8.047,59.009,19.248,5.304,7.596,10.652,6.699,11.009;P＜0.05).Secondly,attachment avoidance had significant negative correlation with both utilization of support and help seeking behaviors in the group of mood disorders (r =-0.470,-0.350; P＜ 0.01).Similarly,avoidant attachment had significant negative correlation with both subjective support and utilization of support respectively (r=-0.232,-0.235 ; P＜0.01) in the group of criminal juveniles.The subjective support had significant positive correlation with solving problem (r=0.272,P＜0.01) and as well as the utilization of support with both solving problem and help seeking behaviors (r=0.258,0.424; P＜ 0.01).Attachment anxiety had significant negative correlation with objective support and had significant positive correlation with self-accusation respectively (r=-0.253,0.300;P＜0.01).Finally,utilization of support as a medium completely effect on the process of avoidant attachment and help seeking behaviors in the group of mood disorder and criminal juveniles.Moreover,subjective support and utilization of support as medium both affected a part in the process of avoidant attachment and solving problem for the group of criminal juveniles.Conclusion First,both adolescents with mood disorders and criminal juveniles have unsafe attachment mode,which are lacked social support and easy to take negative coping styles.Yet,the level of attachment avoidance and subjective support of criminal juveniles was found different compared to teenagers with mood disorder.Second,the attachment styles for both adolescents with mood disorders and criminal juveniles have impact on coping styles by the means of social support,but there were slightly different way.