A software-defined network-based method and system for implementing a content distribution network. An application function, control function, and network entity resource of a CDN are added respectively to an application layer, control layer, and data forwarding layer of an SDN. When a request for a CDN application is received, the SDN application layer generates resource requirement and service scheduling information based on the request, and transmits a reservation request for a resource required by the CDN application to an SDN control layer. The SDN control layer allocates a resource required by the CDN application to combine network load balancing and path policies and to generate a content routing table for data transmission, generating and transmitting L2 and L3 forwarding tables to the SDN data forwarding layer. When it receives content distribution and content delivery requests, the SDN data forwarding layer executes a CDN service-related operation based on the forwarding tables.