Abstract: Researchers have contributed many theories and approaches to figure the boundary of agglomerations and draw the urban agglomeration a reasonable scale, but few studies have quantitatively defined the spatial scope of urban agglomeration from the perspective of integration, which cannot cure the “urban agglomeration disease” such as forming groups blindly and join an urban agglomeration untimely. This study first positions the urban agglomeration as a spatially and temporally variable “community of interests” that cooperating and competing with other systems while internal individuals sharing resources. Then, authors launch a dynamic coupling relationship model of integration of urban agglomeration to test the interactions (include strengths and directions) among the central city and lower-tiered cities around it; applying the theory of metal valence bond that describes the atomic interaction by exchanging electrons internal and external, consistent with the principle of mutual attraction of element allocations among cities. On this basis, defining “coupling distance” and corresponding formula to express the direction and intensity of that interaction, to calculate the integrated region and boundary range of the urban agglomeration. Resort to this theoretical frame, authors first analyze the spatial-temporal changes of blocking effects of the urban agglomeration in different spatial distances. Second, calculating the spatial-temporal changes of the coupling distance among the cities, and then judge the situation and level of urban agglomeration integrating to conclude the suitable spatial scales of the urban agglomeration. In this paper, authors conduct an empirical study on the urban agglomeration along the Middle Reaches of the Yangtze River that including urban agglomeration of Pan-Wuhan, Ring of Changsha-Zhuzhou-Xiangtan urban agglomeration and theurban agglomeration around Poyang Lake, and the analysis results show that:(1) Urban agglomeration of Pan-Wuhan and Ring Changsha-Zhuzhou-Xiangtan urban agglomeration can develop the radius of the integrated regions up to 100 kilometers and 150 kilometers respectively, and the urban agglomeration along the Middle Reaches of the Yangtze River cannot expand the boundary radius exceeds 200 kilometers at present.(2) In terms of the hierarchical system, Ring of Changsha-Zhuzhou-Xiangtan urban agglomeration is second to urban agglomeration of Pan-Wuhan and both exceed the urban agglomeration around Poyang Lake; but the urban agglomeration along the Middle Reaches of the Yangtze River has no heart yet.(3) Analysis of Maturity shows that Ring of Changsha-Zhuzhou-Xiangtan urban agglomeration surpasses the other two as several depressions exist in the middle of urban agglomeration of Pan-Wuhan and two cities are away from the urban agglomeration around Poyang Lake.(4) The members of the urban agglomeration along the Middle Reaches of the Yangtze River are Wuhan, Huanggang, Xiaogan, Changsha-Zhuzhou-Xiangtan urban agglomeration and Yiyang, is smaller to a quarter of the original planning; and “Wuhan & Changsha” will shape into an integrated center.These results offer a scientific reference to the integrated development planning of the urban agglomeration along the Middle Reaches of the Yangtze River.