With China's social and economic development, more people choose to leave their registered permanent residence to work or live in other places, Zhang said at a meeting on China's population issues.
The rapid increase of migration population brings more difficulties to China's family planning administration, Zhang said.
Government statistics show 60 percent of children born out of the family planning are from migration population and China's migration population has reached 147 million currently.
In the future, the registration of migration population in their working and living places other than their registered permanent residence should be strengthened, so as to better monitoring the migration population and improve the family planning administration of them, he said.
Zhang said family planning administration fees for migrant workers will be covered by financial budget in their working cities.
He also called for smoother exchange of information on migration population between the family planning departments and other authorities.