An Instant Messaging, IM, routing method implemented in an IM router network comprising a plurality of IM routers, wherein each IM router of the plurality of IM routers is an IM router that manages one or multiple IM servers, wherein the IM router comprises a management module and a routing module, wherein the management module is used to maintain the IM router's own information and the information of IM servers that the IM router manages, which mainly consists of: Unique identification Router ID, RID, for every IM router in the entire network, Information of one or multiple IM servers that every IM router manages, Unique identification Host ID, HID, of every IM server in the entire network; wherein the routing module is used to provide the IM routing method, wherein the routing method comprises: submitting, by a source IM server, a target IM server's HID to an associated source IM router and sending an addressing request to the associated source IM router by the source IM server; searching, by the associated source IM router, the target IM server's network address in the IM router network based on a routing strategy, wherein the searching comprises forwarding the addressing request to a destination router upon determining that the destination router manages the target IM server sending back, by the destination router, the target IM server's network address to the associated source IM router, once the destination IM router receives the addressing request from the source IM router; forwarding, by the associated source IM router, the target IM server's network address to the source IM server; establishing, by the source IM server, a network connection with the target IM server using the target IM server's network address. Unique identification Router ID, RID, for every IM router in the entire network, Information of one or multiple IM servers that every IM router manages, Unique identification Host ID, HID, of every IM server in the entire network; wherein the routing module is used to provide the IM routing method, wherein the routing method comprises: submitting, by a source IM server, a target IM server's HID to an associated source IM router and sending an addressing request to the associated source IM router by the source IM server; searching, by the associated source IM router, the target IM server's network address in the IM router network based on a routing strategy, wherein the searching comprises forwarding the addressing request to a destination router upon determining that the destination router manages the target IM server sending back, by the destination router, the target IM server's network address to the associated source IM router, once the destination IM router receives the addressing request from the source IM router; forwarding, by the associated source IM router, the target IM server's network address to the source IM server; establishing, by the source IM server, a network connection with the target IM server using the target IM server's network address. submitting, by a source IM server, a target IM server's HID to an associated source IM router and sending an addressing request to the associated source IM router by the source IM server; searching, by the associated source IM router, the target IM server's network address in the IM router network based on a routing strategy, wherein the searching comprises forwarding the addressing request to a destination router upon determining that the destination router manages the target IM server sending back, by the destination router, the target IM server's network address to the associated source IM router, once the destination IM router receives the addressing request from the source IM router; forwarding, by the associated source IM router, the target IM server's network address to the source IM server; establishing, by the source IM server, a network connection with the target IM server using the target IM server's network address.