In recent years, cities in China have achieved unprecedented development. Up to 2011, there have been an urban population of 691 million, and emerged several mega-city regions, such as Beijing, Shanghai, and Hong Kong-Shenzhen-Guangzhou etc. For the significant, large-scale economy and population cluster effect, mega-city regions have become important engines for promoting economic growth and social development. With the hyperactive urban construction, overwhelming urban scale and rapid population growth, there occurs more and more urban geological problems in land utilization, resource supply, environmental protection, hazards prevention and cure in many cities, which become big threats to urban geological safety and constraints on the urban sustainable development. For all cities are constructed on geological objects, the support of Urban Geology is necessary for urban development, and urban geological information has irreplaceable basic role for rapid development of mega-city regions. There is an increasing requirement for the intellectualized, integrated, multi-dimensional and quick-response geological safety supporting system for mega-city regions (GSSSMR) based on the technologies of large spatial databases, GIS, virtual reality and networks, etc., meeting the need of guaranteeing geological resources and geological environment safety, and urban planning, construction, management, mitigating and preventing disasters, etc. After analyzing the requirements of geological information and GSSSMR, we introduce the architecture of GSSSMR. At last, based on the research in this paper, the development and applications of GSSSMR in Beijing, China are presented.