In 2011 a total of 252.78 million migrant workers (an increase of 4.4% compared to 2010) existed in China. Out of these, migrant workers who left their hometown and worked in other provinces accounted for 158.63 million (an increase of 3.4% compared to 2010) and migrant workers who worked within their home provinces reached 94.15 million (an increase of 5.9% compared to 2010). Estimations are that Chinese cities will face an influx of another 243 million migrants by 2025, taking the urban population up to nearly 1 billion people. In the medium and large cities, about half the population will be migrants, which is almost three times the current level.
China’s government influences the pattern of urbanization through the Hukou permanent residence registration system, land-sale policies, infrastructure investment and the incentives offered to local government officials. The other factors influencing migration of people from rural provincial areas to large cities are employment, education, business opportunities and higher standard of living.
Link | Migration in China