Abstract: Megacities with large populations are increasing with the rapid advancing of urbanization,and the urban diseases have broken out,Dealing with urban diseases is a task which brooks no delay.The urban diseases result from the imbalance of area structure,incardination of town and megacities,middle and small cities.So the fundamental way out for strictly controlling the size of population in megacities is to develop towns by society-building,and to integrate urban and rural by reform.Meanwhile promoting urbanization healthily must avoid three kinds of possible inclinations.