<p>Disclosed in embodiments of the present invention are a method and system for acquiring Host Identity Tag (HIT). The method for acquiring HIT includes: an update message containing a newly generated HIT is received; the newly generated HIT is acquired from the update message. By means of directly acquiring the newest HIT and current IP address of the host from the update message, or by means of acquiring the newest HIT from received mapping relation between new and old HIT through a third party server, said system for acquiring HIT can carry out normal communication.</p>
