Abstract: The consequences assessment program for nuclear accidents in emergency decision support system is used to calculate the spatial and temporal distribution of radio nuclides’ concentration and dose and provides advice for making sure the emergency decision. This program was resigned to adjust to the mainstream of computer configuration and software design philosophy. At the same time, the computing capability and the application scope of emergency decision support system were improved by modifying the functions, logical structure and interfaces of the program. In the improved program, actions of relocation, permanent relocation, and food and water control can be considered and the operational intervention levels can be revised. Also, through using browser/server framework unified management of interfaces, the operational limits are broken and maintenance costs of the designed program are decreased. Moreover, the operating efficiency is enhanced by optimizing the data storage scheme. The new version of emergency decision support system could provide more comprehensive technical support to the emergency in nuclear accidents.