Immunosuppressive (IS) agents are effective treatment to avoid acute or chronic rejection after pediatric liver transplantation. However, long-term side effect of IS intaking, like infection, kidney dysfunction, metabolic disorders and developmental retardation, should be aware, especially in pediatric recipients. Spontaneous immune tolerance is defined as recipients who cease to taking IS agents due to multiple reasons and the liver function maintained normal. However, the real ratio and safety of immune tolerance in pediatric liver transplantation recipients are rarely known. We would like to investigate the ratio and safety of spontaneous immune tolerance in pediatric liver transplantation recipients during long-term follow-up by constructing an immune tolerance cohort. In this cohort, long-term pediatric liver transplantation recipients with normal liver function and taking monotherapy of IS would be involved. The IS strategy would be monitored and adjusted according to the Clinical guidelines for pediatric liver transplantation in China(2015). For recipients suffering refractory virus infection, such as EBV or CMV infection, IS will be minimized to assist the clearance of virus until IS was weaned off. Since most of pediatric liver transplantation recipients may encounter chronic EBV or CMV infection within one year after transplantation, they may need IS minimization during follow-up. During the process of IS weaning off, liver function, immunological status and intrahepatic pathology will be closely monitored. If acute rejection or other complications were found, increase of IS dosage or other related treatments will be applied. Immune tolerance is defined as liver function and intrahepatic pathology maintain normal for more than one year after stop taking IS. At the end of study, the ratio of immune tolerance, acute rejection and all types of complications will be assessed.