Abstract: Many Chinese cities have proposed the strategy of polycentric urban development in their master plans. There are still questions about polycentric urban development to be answered: does the evolution of polycentric urban form conform with the master plans? How to identify and measure the morphological and functional urban forms? Previous research has used traditional data to identify the polycentric form, such as population, land use and industry. Nowadays, the emergence of urban big data provides an opportunity to improve the accuracy of identifying urban form and structure. The new methods based on urban big data such as POIs (Points of Interest) can provide accurate and efficient estimation of polycentric urban structure compared with traditional methods. Using 408 768 POIs data in Chongqing urban area, this paper identified the overall pattern of polycentric structure and the polycentric structures of different functions by considering the spatial distribution and the degree of aggregation of POIs. This paper found that Chongqing as a mountain city, constrained by natural condition and stimulated by urban planning, has formed a typical “polycentric form composed of multiple subcenters and clusters”. The distribution of POIs shows that the subcenters have relatively comprehensive urban functions, such as financing, shopping, dwelling and recreation. The main center and several sub-centers in Chongqing gather within the inner ring road. The sub-centers have significant differences in terms of urban development and spatial aggregation. The peripheral subcenters such as Xiyong and Chayuan have lagged behind other subcenters. Therefore, urban aggregation need to be strengthened in the near future.

Key words: Chongqing, POI, polycentric form, urban spatial structure