In China，the number of the medium-sized cities has increased significantly. The distribution patterns of cities in four regions remain essentially unchanged. The main share of urban population is from metropolis，and the main shares of newly increasing number of urban population are from mega-cities and medium-sized cities. Urban agglomeration has developed rapidly and the function of cities has significantly enhanced. However，the development of urban system is not perfect；the aggregation effect of mega-cities still needs to be improved；the built-up areas have expanded too fast，with the weak aggregation effect of the towns. During the period of the 12th Five-Year Plan，we should take some measures as follows：to make full use of urban aggregation effect，maintaining the basic stability of the national urban districts；to positively build international metropolis and national center cities；to implement the differentiated policies for regional urban system optimization；to promote some medium-sized cities to grow up into big cities and some big cities to grow up into metropolis；to accelerate the development of counties，building a number of key towns.