Under the situation of almost negative growth of registered household population，large scale trans-regional flow of Chinese population is the main driving factor of population expansion in large cities. Firstly，we use some rigid data such as the total number of urban mobile phone users at the end of a year to estimate the size of the population of the major cities above prefecture-level cities in China，the results show that there are sixty-two cities with over two million people in China. Secondly，we analyze the effect and the cost of population regulation by non-market means of population control by taking example of Beijing Olympic Games，Shanghai World Expo and Guangzhou Asian Games，the results indicate that the city population size regulation mainly by local governmental administrative means has significant effect in short-term，but once the regulation is easing，the city population rapidly returns to its original state in short-term. Thirdly，we explore the spatial distribution and growth evolution of Japanese urban population，the results reveal that the imbalance of regional economic development is the key factor to lead to the floating of the population among different cities and different regions. Finally，we conduct the estimation and analysis of the population evolution in the prefecture-level cities of Guangdong Province，the results demonstrate that population flowing from the core cities at Pearl River Delta to their surrounding cities is mainly the back-flow with the industrial transfer. Under market economy framework，administrative means should not be mainly used to regulate population growth in big cities，however，market-oriented means such as industrial upgrading and transfer should be used to control urban population structure.