The current focus of earthquake disaster prevention and mitigation work has shifted from postdisaster emergency rescue to predisaster risk prevention and control and from passive prevention of earthquake disasters to active reduction of earthquake disaster risks. The construction of earthquake disaster risk assessment and service systems can provide strong support for reducing earthquake disaster risks and enhancing the ability to prevent earthquake disasters. This paper started with the earthquake disaster risk situation of Sichuan Province, which was characterized by high risks of seismic and geological hazards, high exposure of disaster-bearing bodies, and significant differences in vulnerability of disaster-bearing bodies. Based on the needs and objectives of earthquake disaster risk prevention and control, it focused on earthquake disaster risk assessment, zonation, and information service. The overall framework, function, and business process of the earthquake disaster risk assessment and service system in Sichuan Province were designed and developed using big data, cloud computing, spatial information, and other technologies. The system integrated multisource heterogeneous earthquake disaster risk data, thus promoting the process of earthquake disaster risk assessment and further improving the information service capability for earthquake disaster risk prevention and control.