Objective To observe the influence of Epstein-Barr virus(EBV) infection on T cell subsets in children with infectious mononucleosis(IM).Methods Eighty children patients with IM in the Hanzhong Municipal People's Hospital from January 2013 to January 2016 were chosen as the study subjects and received the anti-virus therapy.The negative conversion rate of EBV-DNA after treatment was observed.The distributions of T cell subsets werecompared between the children patients with EBV-DNA positive and patients with EBV-DNA negative.The related factors of EBV-DNA non-negative conversion were analyzed.Results After treatment,67 children cases (83.75％) were EBV-DNA negative conversion.The proportions of CD3+ and CD8+ after treatment in the EBV-DNA negative group were lower than those in the EBV-DNA positive group,and the proportion of CD4+ and CD4+/CD8+ were higher than those in the EBV DNA positive group,the difference had statistical significance (P＜0.05).In the analysis on the related factors in the children patients with EBV DNA non-negative conversion,the gender,WBC count and lymphocyte count had no significant correlation with EBV-DNA negative conversion(P＞ 0.05),while interferon use,age and initial Ct demonstrated significant correlation with EBV-DNA non-negative conversion(P＜0.05).Conclusion EBV infection can lead to disturbance of T cell subsets in children with IM,so clinic should adopt an active anti-virus treatment.