Not easy to leave?

Long hours commuting and poor living prospects have made big cities unattractive for migrants. However, leaving is not an easy choice either.

Tang said he does not actually like big cities, but there are few jobs in his hometown of Chengde in north China's Hebei Province.

"Small towns like Chengde do not have jobs for university graduates majoring in software engineering. That is why I have to struggle for a living in Tianjin," he said.

Few of the migrants are willing to go back to their rural homes and live off farming, because they want to earn money for their next generation.

The central authorities are aware of the inner city unbalance caused by the country's urbanization process.

Chinese President Xi Jinping said at a meeting in July that second and third-tier cities must improve their attractiveness to the migrant population.

Xiao Yanyang, vice professor of the department of urban planning with Hunan University, said migrant workers crowded in mega-cities should be encouraged to move to second and third-tier cities to improve their living conditions.

He said Chinese cities used to be movitated by population flow from rural areas to cities. However, for further urbanization, infrastructure construction should outpace population growth to make cities more attractive to live in.