Large earthquakes frequently occurred and caused substantial damage and losses in Chinese densely populated urban areas. It is worth clarifying that the existing earthquake loss assessment tools in China do not consider its special characteristics (e.g., tectonics, geology and building inventory). In this paper, an integrated framework for earthquake loss assessment in China is proposed and a geographic information system (GIS)-based system, referred to as China Earthquake Disaster Loss Assessment System, is developed. The individual building is considered as the basic geographical unit and described in three levels (i.e., basic attributes, structural performance parameters, and functional parameters. A three-step data collection method is proposed, and the mobile GIS-based field collection tool is developed. A broad, reasonable, and upgradeable building typology is then presented for the seismic fragility assessment of building blocks. A new economic loss model and casualty model are also presented by considering the characteristics of economics and population. The proposed methodology is implemented in Baqiao District, and the estimation of economic losses and casualties under a scenario earthquake is discussed, which can provide information for urban disaster risk assessment and mitigation.