Abstract: In1993the population natural growth rate of Shanghai city first appeared negative.Since then the fertility of shanghai has continuously been negative growth,and the increase of the absolute population numbers was due to migration,and meanwhile,the fertility of the big cities:such as Beijing,Tianjin,and Shenyang were also declining dramatically.By contrast,the fertility of Guangdong province has remained high though Guangdong' s economic development has been in the leading position in China.On the basis of the comparison,this paper argues that only when marketing economy combines with urbanization and modernization,it can effectively control population.