The urban agglomerations in Northeast China group grew up in the special historical period, under a special economic background, and its unique structure and function has been the regional labor division of the old industrial bases in Northeast China, even controled the economy development in Northeast China. According to the connotation of urban agglomeration, cities group and urban agglomeration group, this paper pointed out there currently exist objectively three large urban agglomerations, namely, urban agglomerations of Central Southern Liaoning, Central Jilin and Harbin-Daqing-Qiqihar in Northeast China. According to the formation, development process and the present situation, Central Southern Liaoning has already developed into a mature urban agglomeration, while Central Jilin and Harbin-Daqing-Qiqihar are still in intermediate stage of urban group development. Thus it has been formed a spatial structure with'an agglomeration and two groups’in Northeast China. By the analysis on the urban extroversion meritorious energy and urban flows intensity in three large urban agglomerations in Northeast China, it was found that there is not any city’s location quotient for the main extrovert service of the urban agglomeration being greater than 1. And their development levels were lower than that of domestic advanced urban agglomeration. The future development should focus on urban agglomeration organization structure, network development pattern, function division and complementary, development relationship coordination, etc., and further control and optimization are needed. Central Southern Liaoning should strengthen the benefit mechanism and efficiency mechanism when the heavy industry and equipment manufacturing continuously develop; Central Jilin should consolidate industrial relation, sticking to the development of automobile industry and emerging industries; Harbin-Daqing-Qiqihar should lay emphasis on resources-substitute industry and emerging industries.