On The Economic Increasing Effect Of Urban Scale Agglomeration

China is in a key period of accelerating urbanization and adjustment of industrial structure, so it is very important to plan a scientific urban development strategy. Based on the theory analysis of the economic increasing effect of urban scale agglomeration, the paper gives a research on Chinese urbanization and the existing system of city's population scale. The paper points out, although the urbanization of our country has a high speed, it is still lagged behind the industrialization. The amount of small city is too big, which is disadvantage to the development of the third industry and the optimization of industrial structure. The regional distribution of different scale city is not in the balance. After that, by sampling 278 cities of China, we make a calculation of the economic increasing effect of urban scale agglomeration. And we draw the conclusion that the city scale which is between 300 thousand and 15 million is proper, which is below 300 thousand or exceed 15 million is not proper, which is between 1 million and 5 million is the best scale. From the analysis above, the paper puts forward coordinated urban developing strategy to develop international cities, to enhance middle-scale cities and present small cities.