关键词: 首都圈 , 首都经济 , 经济结构

Abstract: Generally，the economic structure of capital cities in the world includes eight constituent elements：services，headquarters，knowledge，lowcarbon，parks，rail，airport and harborCapital economic always first experiences polarization effects，and then turns to diffusion effects，and ultimately forms metropolitan economy in a certain areaBy collecting comparable and available data，four international metropolitan areas，London，Paris，Seoul and Tokyo，are compared with Beijing in eight aspects，including service economy，headquarters economy，the knowledge economy，green economy，industrial parks economy，prorail economy，airport neighboring economy and harbor neighboring economyPoor threshold method is used for comprehensive comparison，the results show as followsAs a capital，Beijing has economic development strength，ranking in the middleIf Beijing，Tianjin and Hebei are treated as a whole economic circle，it ranks behind other four international citiesThe truth is that its difficult to resolve “big city disease” on its own strength，only by achieving the integration of Beijing，Tianjin，Hebei and realizing joint development，namely establishing metropolitan economic in whole area，which can achieve optimization and upgrading of capital economic structure

Key words: capital circle , capital economy , economic structure