Abstract: While the cooperative development of Beijing Tianjin Hebei becoming national strategy of China，the research about Beijing Tianjin Hebei metropolitan areas and its carrying capacity also has been enriched and deepened.The majority of existed research focused on the connotation of carrying capacity and calculation about extent of single carrying capacity，while the current research neglected coupling relationship of comprehensive carrying capacity system.Based on evolutionary systems theories such as dissipative structure theory，synergy theory and catastrophe theory，this paper described and analyzed coupling and motivating mechanism of comprehensive carrying capacity system in Beijing Tianjin Hebei metropolitan areas，by establishing coupling model of comprehensive urban carrying capacity system.This paper would provide certain suggestions on improving research framework of carrying capacity.

Key words: BeijingTianjinHebei, urban comprehensive carrying capacity, coupling model, motivating mechanism