The polycentric urban model shows that there were two density centers in Nanjing in 1990s. (4)Compared with other cities, the population suburbanization of Nanjing in 1990s lagged behind others.

• （4）通过与其它城市的比较看，1990年代北京、上海等城市都已进入了人口郊区化的显著阶段，而南京市人口郊区化现象相对滞后，还停留在郊区化的初级阶段，刚刚表现了郊区化的前兆。