The urban environmental security becomes a new hot spot of environmental problems at present. The environmental security is raised in correspondance with the environmental calamity. This article puts forwad urban environmental security and the preparatory scheme for heavy environmental disaster rescue for Beijing based on analysis of some insecurity environmental factors of Beijing. The research contents include: The Beijing urban environmental security; The environmental disaster comprehensive zoning in Beijing; The information system supporting the management and decision about environmental disaster;The rescue and prevention scheme of urban meterological disaster;The forest fire prevention of Beijing by GIS technology;The cause and prevention strategy of dust storm;The health security and epidemic prevention in Beijing;The study of earthquake disaster prevention; Transform, perfection and construction of urban lifeline system engineering; The rescue scheme for serious environmental disaster; The effect of environmental disaster on urban economic development in Beijing.