Demographic trend for three decades in Beijing.

Beijing's permanent population exceeded 20 million, about 2.6 times that of London and 2.5 times more than New York. As a megacity, Beijing is challenged by a complex mixture of "urban diseases", such as air pollution and congestion.

Owing to limited resources, people with Beijing "hukou" enjoy better educational opportunities, employment support, care for senior citizens and social welfare.

Previously, migrant citizens could only apply for temporary residential permits, with none of the rights or benefits enjoyed by permanent residents.

Similar point-based residency permit systems have already been put into use in cities like Shanghai, Guangzhou and Tianjin.

In Guangzhou, applicants' educational background, skill level and social security records are converted into points. Each year, nearly 3,000 migrants can obtain "hukou" in the city.

Beijing has a strict system of household registration. More than eight million migrants lived and worked in the capital last year. The new system allows them to see the chance of becoming a real part of the city.

A migrant surnamed Zhang, who has worked for nearly ten years at an investment company in Beijing, said the new system seems to be more equal and transparent.

"Beijing needs to control population growth and meet demands of migrants to obtain 'hukou' at the same time. Once the pilot program turns out to be successful, it can set a good example to other places," said Niu Fengrui, a researcher with the Institute for Urban and Environmental Studies under the Chinese Academy of Social Sciences.

Beijing can control its population growth by transferring some of the capital's functions to neighboring regions rather than by adopting stricter household registration system, said Yi Peng, a researcher of PanGoal, a public policy research Institution.