Method, device and system for dividing domain for data communication network

The present invention relates to a method, device and system for dividing a domain for a data communication network. The method for dividing a domain for a data communication network comprises: receiving, by a target node, a command for dividing a domain, the command for dividing a domain comprising information about various target nodes needing to be divided from an old domain to a new domain and an identifier of the new domain; judging, by the target node, whether the distance between itself and a gateway of the old domain is the minimum of distances between various target nodes and the gateway according to network topology information about the old domain and information about various target nodes; in the case that the distance between the target node and the gateway is the minimum of the distances between various target nodes and the gateway, setting, by the target node, itself to be a boundary point. In the embodiments of the present invention, in accordance with network topology information and information about various target nodes, if the distance between a target node itself and a gateway is the minimum of distances between various target nodes and the gateway, then the target node sets itself to be a boundary point; the determining process is simple, which may reduce detachment caused by the fault of manually planning the boundary point or searching the boundary point.