This book mainly focuses on the status, trends and countermeasures of carrying capacity in the Beijing-Tianjin-Hebei metropolitan region. It presents the results a comprehensive survey and systematic research on the carrying capacity of this region and its mega-cities, conducted in the hope of providing decision-making support for the governments of this region. The primary goals are to be able to actively respond to the new challenges of global climate changes and environmental resource constraints; fully practice green development concepts; and actively promote transformation in the development of the population, resources, environment, economics, society and ecology in this region.