Through analyzing the current situation of population trans-provincially outflow，it finds that there are some serious illegal fertility problems among this group of population like having extra child or hiding for having extra child. The dilemmas includes difficult to grasp the real marriage and fertility information of the trans-provincially outflow population，lack of timely and effective information exchange channels，and different basic public services they can enjoy，and so on. At same time，it also analyzes the reasons of the exiting problems. To build an information sharing mechanism among provinces，it puts forwards that make regulations from the national level and strengthen the provincial information sharing system. To improve the management level of family plan work，it can construct a complementary mechanism covering inflow places oriented two-way interactive management，and entrusting the inflow places to handle the services.