The present invention discloses a method for obtaining an Internet protocol header replacement mapping, which belong to the field of communications technologies. The method includes: obtaining, by a network node, fixed IP header information which is bound to a UE, where the network node is an MME or an eNB or a PGW or an SGW; establishing an IP header replacement mapping according to the fixed IP header information, where the IP header replacement mapping is correspondence between the fixed IP header information and an index or a bearer; and performing data transmission with the UE according to the IP header replacement mapping. In the present invention, the network node establishes the IP header replacement mapping according to the obtained fixed IP header information which is bound to the UE, the method is more flexible.