Abstract: Emergency decision-making to Marine Pressurized-Water Reactor（MPWR） was severely restricted by the complex environment.To enhance the emergency decision-making ability of MPWR,reducing（EVA） and Environment Agent（ENA） were designed.The MAS were with the characteristics of autonomy,reactivity and initiative,which were fully used in the system to make effective decision for emergencies.the effect of emergencies,an emergency Decision-making Support System（DSS） which based on Multi-agent System（MAS） was presented.In the system,the HLA/RTI was used as the support environment,and the structure and the Control Agent（SCA）,Analyse Agent（AA）,Countermeasure Agent（CA）,Evaluation Agent