Abstract: Based on the GO methodology and Markov method,the dynamic analysis of emergency die-sel generator system for protecting the nuclear power plant from Station Blackout,which is caused by Loss of Offsite Power event,is made with duration of 24 hours.In addition,the accurate reliability calculation problem is solved for the repairable system with dependant maintenance relation,and the logic relation of emergency response system is fully simulated by creating the "Backup Operator" of the GO methodology.By combining the two reliability analysis methods,which is used suitably for the emergency response system of diesel generators with dependant maintenance relation,the application range for the two methods is expanded,and the effect of station blackout event on the safety operation of nuclear power plants can be obtained more accurately.