Using methods such as the center of gravity model, the social network analysis and the spatial lag model, this paper analyzes the spatial pattern and the influencing mechanism of floating population agglomeration in three city clusters: Beijing-Tianjin- Hebei region, Yangtze River Delta region and Pearl River Delta. Our findings suggest that the scale of floating population in the three major city clusters continued to grow, but the growth rate of both the size and density of the floating population has slowed down. In addition, we find that the gravity center of the floating population moved to economically developed and highly populated cities, and approached the gravity center of permanent resident population gradually. The social network structure of three city clusters is increasingly dense, representing as a spatial pattern of the star-shaped, multi-center divergent and center-peripheral hierarchical structure network, respectively. The influencing mechanism results show that high housing price and environmental pollution have weakened the attractiveness of economic factors to the floating population agglomeration in the Beijing-Tianjin-Hebei region, while higher public service and opening-up have attracted the floating population to continue to flow into the Yangtze River Delta and the Pearl River Delta, respectively. The results provide policy suggestions for different urban clusters to make scientific development plans and optimize population distribution.
