The National Seismic Intensity Rapid Reporting and Early Warning project of China has built largest earthquake intensity rapid reporting and early warning observation station network in the world. With a total of over 15,000 stations,it is about to be put into full testing operation. Customized software is one of the core components of the early warning project,which will realize a comprehensive upgrade of China's earthquake observation data processing system. In this paper,the overall design of customized software is introduced from the aspects of design ideas,overall architecture,subsystem functions,deployment methods,performance indicators and key technical indicators. Such design with high efficient performance of data processing,emergency earthquake information providing,meets the functional requirements of the early warning,so that the early warning project has high stability and reliability,low latency,comprehensive data service capabilities and technical support capabilities. As the results,the two major functions of both earthquake early warning and intensity quick report are implemented,which makes the earthquake prevention and disaster reduction more efficient.