The present invention discloss an address translation method simultaneously supporting one-to-one and many-to-many under the PAT mode. The method mainly includes the following steps: firstly, defining protocol type supported by IP address translation and its correspondent hashing algorithm adopted by IP address translation, and defining the aggregation of public network IP address pool and publicnetwork pont used by IP address translation, then establishing a two-dimensional array of index pointer for storage respectively directed against one-to-one address translation unit and port address translation unit, when the transferred message is undergone the process of IP address translation, according to the hashing algorithm the index pointer can be found out from the above-mentioned array so as to implement IP address translation.