The disclosure discloses a method and a system for establishing an associated bidirectional Label-Switched Path (LSP). The method includes the following steps: a head node sends a PATH message for establishing or updating an LSP to an end node, wherein the message carries an object for identifying association; the end node sends to the head node a PATH message for establishing or updating an LSP as a reverse LSP corresponding to the above LSP, wherein the message carries an object for identifying association; in the case that the attributes of the objects for identifying association carried in the PATH messages sent by the head node and the end node are the same, the LSP and the reverse LSP are associated with each other by the head node and the end node and become an associated bidirectional LSP. The method for establishing an associated bidirectional LSP in the disclosure can be applied to transition from a Multi-Protocol Label Switching (MPLS) network to a MPLS-Transport Profile (MPLS-TP) network and binding a reverse LSP with a unidirectional LSP.