The invention discloses a method and device for end-to-end three-layer virtual link, wherein the method includes the following steps: a data network management collects resource information of a first Broadband Remote Access Server (BRAS) which is any BRAS; determining the number M of Optical Line Terminals (OLTs) connected with the first BRAS according to network topological information; associating the resource information of the first BRAS with the IP addresses of the M OLTS according to the network topological information, thereby obtaining a three-layer virtual link of the first BRAS; and cycling the operation, and traversing all the other BRASs except the first BRAS, thereby obtaining three-layer virtual links of all the BRASs.