The planning and construction of the Beijing City Sub-center is an important strategy for resolving the functions of the non-capital and promoting the coordinated development of Beijing-Tianjin-Hebei. This is a millennium plan and a national event. From the overall coordination mechanism，industrial docking cooperation，major project construction，and policy innovation breakthroughs，the paper stands in a larger scale space and analyzes the background，current situation and problems of the coordinated development of Beijing City Sub-center and Langfang North Three Counties. The research proposes that the coordinated development of the both sides and the construction of the Beijing-Tianjin-Hebei coordinated development demonstration zone.