The population growth rate of the four first-tier cities in the north, Guangzhou and Shenzhen has gradually slowed down and even experienced negative growth. There are the following reasons behind this: 1. High housing prices: housing prices in the north, Guangzhou and Shenzhen are generally higher. For some young people, it is difficult and expensive to buy a house, which is one of the reasons why they choose to leave these cities. 2. High cost of living: In addition to high housing prices, the cost of living in the north, Guangzhou and Shenzhen is also relatively high, such as transportation, food, entertainment, etc., which makes some people choose to leave. 3. Population aging: With the aggravation of population aging, the growth rate of urban population will naturally slow down or even have negative growth. 4. Industrial transfer: With the advancement of national industrial transfer, some enterprises and talents began to transfer to the central and western regions, which also led to a decrease in the population of North, Guangzhou and Shenzhen. The above reasons show that the development of the four first-tier cities in the north, Guangzhou and Shenzhen has entered a new stage, and the reduction and mobility of urban population have also brought some signals: 1. Intensified urban competition: The decrease and mobility of the population in the four first-tier cities means that urban competition will be further intensified, and cities need more advantages to attract talents and enterprises. 2. Diversification of population flow: The population flow trend will be more diversified, not only from rural areas to cities, but also from first-tier cities to second-and third-tier cities. 3. Adjustment of urban development strategy: cities need to pay more attention to population quality and cultural construction in order to attract more high-end talents and innovative enterprises. 4. Importance of coordinated regional development: With the transfer of some talents and enterprises to the central and western regions, it also strengthens the importance of coordinated regional development, and all localities need to cooperate better to form a better development pattern.