The disclosure provides a method and apparatus for a dual-stack Mobile Node (MN) to roam in an IPv4 network. The apparatus mainly includes a Foreign Home Agent (FHA). The method mainly includes: acquiring, by the MN, a temporary IPv4 address THOA that the FHA assigns to the MN, and registering its IPv4 Care-of Address (COA) in the FHA; and delivering, by the FHA, a packet between the MN and a Corresponding Node (CN) or Home Agent (HA), according to information about the IPv4 COA, which is assigned for the MN and has been registered by the MN in the FHA. With the method of the invention, a routing solution may be implemented for a dual-stack MN to roam from an IPv6 network to an IPv4 network.