The urban function mix is a key element in the scheme of improving the efficiency and the vitality. Also, it serves as a significant principle in the modern urban planning. Therefore, the determination of the function mix level of a city and the adoption of effective optimization strategies are essential for the construction of human-oriented cities. A new approach is proposed in this paper for the evaluation of the urban function mix based on the multi-source geospatial big data by combining the spatial layout and the actual condition of the utilization together, to incorporate the characteristics of both supply and demand of urban functions. The method is then applied to explore the spatial characteristics and factors of the urban function mix of the region inside the sixth ring of Beijing. The results suggest that urban function is a common phenomenon in Beijing, and it should be considered as a fundamental principle in the urban planning and management. From the perspective of spatial characteristics, the density of the urban function mix follows a distance decay law, which reflects the significant influence of the location and the polycentric structure. Furthermore, the relationship between the mix ratio and the spatial pattern of urban functions in blocks, dominated by different functions, is discussed. Finally, practical suggestions are made to optimize the urban function mix and to improve the urban fine governance for urban planners and decision makers.

spatio-temporal big data  /  urban function mixture  /  quantitative measurement  /  urban fine governance