Abstract: The paper aims to generalize the characteristics and evolution of spatial structure in Shanghai Metropolitan Area, and also to compare the basic results with those of Beijing Metropolitan Area. To demonstrate the spatial evolution of both employment and population distribution in Shanghai, we have applied nonparametric methods to the analysis, which contains two perspectives of ‘agglomeration-dispersion’ and ‘monocentricity-polycentricity’. Our study has concluded that there is a continuous and evident dispersion in both population and employment distribution since the 1990s, and our study has identified the significant concentrated sub-centers in peripheral areas, which strengthened the polycentricity of the metropolitan area. As for Beijing, the overall trend of population evolution tends to be dispersed and polycentric, but the spatial distribution of employment is generally concentrated in central areas, which is contrary to the decentralization of population. According to our comparative analysis, the employment and population spatial distributions match better in Shanghai. We have also discussed about the reasons for different phenomena in Shanghai and Beijing. Differences of industrial structure between Beijing and Shanghai may be one of the most important causes for the employment distribution disparity, owing to the fact that Shanghai's manufacturing share is higher than Beijing's and the industrial dispersion helps promote the ability of absorbing employment in suburban areas and form the polycentric urban spatial structure. As for Beijing, service industry plays a significant role in recent years. Service industry often requires face-to-face communication, as a result, enterprises tend to form an agglomeration and reinforce the centralization, leading to a much more monocentric urban spatial structure. Meanwhile, in both Beijing and Shanghai, the population and employment sizes in central districts still matter a lot, which has already made some employment sub-centers not significant. Therefore, it is necessary for megacities to restrict the growth boundaries in central districts, so as to prevent inefficient spatial extension. Also, it is worthwhile to reinforce the agglomeration economies of sub-centers in peripheral areas to relieve the crowded effect in central areas.

Key words: patial distribution of employment and population, polycentricity, Shanghai Metropolitan Area, urban spatial structure, dispersion