The present invention discloses a method, system of fault detection for pseudo wires (PW) and a provider edge router (PE) thereof. The method includes the following. A remote PE receives, from a local PE, a first bonding relationship between a PW and an LSP of which the starting point is the local PE. After the remote PE detects a fault of the LSP, the remote PE determines a fault of the PW based on the detected fault of the LSP, a second bonding relationship between the PW and an LSP of which the starting point is the remote PE, and the received first bonding relationship, wherein the second bonding relationship is pre-configured at the remote PE. The method, system and PE of fault detection for a pseudo wire according to embodiments of the present invention can detect a fault of the PW precisely, ensuring the consistency of PW statuses detected by PEs at the two ends of the PW.