The authors found that the past quantitative study on regional spatial structure of the Chinese urban system that was based on the random distribution model of Poisson's equation was imperfect, because the contemporary Chinese cities did not fit the character of the random distribution. A gravity model of the cities spatial distribution was formatted by virtue of Newtonian Dynamical Equation to improve the random distribution model, and made a quantitative study of the Chinese cities by taking province-level administrative regions for spatial cells and using the data of 2002. The conclusions are summed up as follows: first, the urban spatial structure of China was composed of 6 mass-clusters of urban accumulative regions, 10 strip-clusters of urban accumulative regions and 8 urban groups with metropolis as the core; second, multi-cores and multi-clusters urban accumulative regions were mostly distributed in the east provinces of China, sole-core and sole-cluster urban accumulative regions were mostly distributed in mid-China, and large urban groups appeared in the west. The difference of cities development levels was obvious among the three zones, and gradient-phenomenon is very distinct.