Embodiments of the present disclosure disclose a peer selection method, network device, and system. The method includes: receiving a network resource download request sent by a requesting peer, and sending a peer identifier of the requesting peer and a peer identifier of a candidate peer to a server, so that the server queries a storage path cost of the candidate peer according to a preset network map and returns a query result, where the candidate peer owns a network resource requested by the requesting peer; and receiving the query result returned by the server, and notifying the requesting peer of the query result. According to embodiments of the present disclosure, costs between a peer and network storages of other peers can be queried, and a network storage of the lowest cost can be further selected for downloading the network resource.