A method for implementing traffic engineering, TE, in layer 2, L2, network, includes: collecting TE information which is sent by respective L2 network devices according to extended network topology discovery protocol; calculating and deploying constraint-based routing with the collected TE information of the L2 network. The existing network topology discovery protocol is adopted in the L2 network, so that the L2 network devices do not have to support protocols such as OSPF and ISIS. Therefore, the present invention is helpful to avoid resource consumption of OSPF and ISIS protocols on the L2 network devices and reduce the complexity in implementation of the TE over the L2 network.