Disclosed are a data download method and device. The method comprises: based on a peer-to-peer network (P2P) manner, in the process of downloading data from a content delivery network (CDN), when detecting that the total number of clients connected to a locally existing P2P is updated, updating, by a client, a local download decision, a data identifier of data already downloaded and a data identifier of data to be downloaded being recorded in the local download decision (100); sending, by the client, the local download decision to other clients connected to the locally existing P2P, and receiving download decisions sent by other clients connected to the locally existing P2P (110); and comparing, by the client, the local download decision with the received download decisions, and when it is determined that the local download decision and any received download decision contain the same data identifier according to the comparison result, determining an adjustment policy with respect to the local download decision based on a data download state characterized by the same data identifier (120). This method avoids the repetitive download of data already downloaded, thereby effectively saving network resources.