A method for supporting indication of a failure event to a source access system is provided. The method includes notifying, by the source access system, information of a source cell to a target access system, routing, by the target access system, a message to the base station or the base station controller of the source access through a core network by use of the information of the source cell received from the source access system when the target access system needs to transmit a message to the source access system. By use of the method provided by the present disclosure, a problem of mobility robustness optimization (MRO) among different radio access technology (RAT) may be notified to the source access system, so as to avoid impact for a terminal, reduce operator configuration.