Background: Tuberculosis remains the major public health problem and it is the most Catastrophic diseases in the world. People living with human immune virus are more likely to develop TB than others. Especially children with human immune virus have a higher risk of develop tuberculosis. Globally, an estimated 10.0 million people had tuberculosis disease in 2019, and there were an estimated 208, 000 deaths among people living with human immune virus. Even if there are few study regarding to incidence of tuberculosis among HIV positive children but their median time is inconsistence between studies. Therefore the aim of this study is to assess the median time to develop tuberculosis and its predictors among human immune virus positive children on antiretroviral therapy in Bahirdar city. Objective:-To determine the time to develop tuberculosis and its predictors among children on ART at Bahirdar city, North West Ethiopia, 2021 Methods:- Institution based retrospective follow-up study was conducted in 428 children on ART selected by simple random sampling from 2011-2020 in Bahirdar city antiretroviral therapy centers. The collected data were entered to EPI DATA version 3.1 and export to STATA™ 14.1 for analyzes. Kaplan-Meier curve was use to estimate the probability of tuberculosis -free survival of children. Cox regression model was used to identify independent predictors of TB infection .The proportional hazard and global goodness of fit assumption was checked. Result:-Tuberculosis incidence was high among children on antiretroviral therapy, especially in the first one year after antiretroviral therapy. Overall incidence density 3.37 (95% CI: 2.612; 4.334) cases per 100 person-years of observation History of contact with active TB (AHR=3.64,cl:1.73-7.67), missed isoniazid preventive therapy(AHR=2.55 cl,1.12-5.81), advanced stages of who clinical stage(ARH=2.18,cl:1.05-4.53),poor adherenceofdrug(ARH=3.49,cl:1.38-8.8)andvaccinationstatus(AHR=2.89,cl:1.89-7.28)were significantly associated with the incidence of tuberculosis. Conclusion:- The development of TB among children on anti-retroviral therapy is high within the first one year after enrolment. The risk of develop TB was higher for those who are incomplete vaccination, had poor adherence, missed Isoniazid prophylaxis, history of TB contact and advanced WHO clinical stage. Keywords: time to develop, predictors, children on ART, TB, Amhara region.