Cross-regional power grid interconnection, high-capacity DC power transmission and the operating characteristics of delay and uncertainty with the third defense line of power system put forward more advanced demand on emergency control technology. The analysis of recent catastrophic blackouts occurred in many countries points out that the cross-grid large-capacity power flow transfer and continuing to deterioration of the security and stability situation of isolated power grid after power grid tie-line splitting due to lack of rapid active control measures are the key cause that power system occurs seriously events, such as successive splitting, even collapse of power system. On the basis of analyzing the factors that probably cause power grids separation and the problems of safety and security for the isolated power grid after power grid tie-line splitting, an emergency control scheme of isolated power grid based on splitting information triggering is presented, which adopts the method of delaminated control involving compound master control station, control information substation and execution control station and the coordination control of off-line & on-line. Through cost performance with off-line and the quantized control index between AC/DC control measures with on-line to search the optimal control strategies, it is ensured that quick, active and sequential control measures can be obtained with the emergency state of the isolated power grid after power system separation. The method is verified by simulation.