The paper puts forward a separating policy of routing and transmitting for GGSN based on OSPF to aim at decreasing the complexity of routing and transmitting for GGSN. By means of modifying the OSPF and the path of network topology, we successfully implement the separating the routing module from the transmitting module. In addition, the method can decrease the rate of network traffic and arrive at the aim to the seamless handover for system. The simulation results show that the above policy meet the requirement of GGSN and has been testified in the experiment effectively.