A path verification method and a related device are provided, and are used in the field of communication technologies. The method includes: A network device obtains path information of a packet forwarding path, where the packet forwarding path passes through a third autonomous system AS, a second AS, and a first AS in sequence, and the third AS, the second AS, and the first AS are sequentially adjacent. The network device determines a business relationship of a first AS pair and a business relationship of a second AS pair, where the first AS pair includes the first AS and the second AS that are sequentially arranged, and the second AS pair includes the second AS and the third AS that are sequentially arranged. The network device determines, based on the business relationship of the first AS pair and the business relationship of the second AS pair, whether the packet forwarding path is valid. In embodiments of this application, whether a path is valid needs to be determined based on business relationships of neighboring AS pairs, to more accurately verify a leakage status of P2P routing information, so that a verification result is more trustworthy.