A method for heterogeneous addressing mapping is provided according to the embodiments of the present invention. The method includes: assigning, by an Interworking Function entity (IWF), a first identification or a first address to a Diameter protocol node; mapping a received Diameter protocol message sent from the Diameter protocol node into a Mobile Application Part (MAP) protocol message, and sending the mapped MAP protocol message to an MAP protocol node using the first address assigned by the IWF as a source address or using the first identification assigned by the IWF as a source identification. The present invention also provides a system and an apparatus for heterogeneous addressing mapping. According to the embodiments of the present invention, when the Diameter node is communicating with the MAP node via the Interworking Function entity, the method for mapping the node identification for each other as well as the addressing relationship corresponding to each identification are provided. Thus, the problems that the communication with each other cannot be realized due to different identification addressing approaches are solved.