The invention discloses a far-end PW BFD descriptor learning method and system based on a network processor, and the method specifically comprises the following steps: S1, setting an internal table item on the network processor at a local end, wherein the table item comprises the corresponding relation between a PW label and a local end BFD descriptor; S2, enabling the network processor to extract a BFD message after the BFD transmitted by a far end reaches the network processor, analyzing the BFD message, extracting the PW label as a KEY for searching the internal table item, and enabling the network processor to obtain a corresponding local end BFD descriptor according to the corresponding relation between the PW label and the local end BFD descriptor; S3, enabling the network processor to write the local end BFD descriptor in the BFD message, and completing the learning of the BFD descriptor. According to the invention, the network processor learns the BFD descriptor, and on control software needs to participate in the whole learning process, thereby solving a learning process of the BFD descriptor in a cross-domain scene. The method is simple in implementation flow, and is high in reliability.