the paper first analyzes the basic theory of the CDN (Content Delivery Network) audio and video system and the P2P (peer to peer) audio and video system, and presents its own limitations of each kind of the architecture. Then a hybrid model has been proposed, which integrates CDN and P2P to build the audio and video public network platform. The paper describes the architecture of the hybrid model, its work processes and characters in detail. The model takes full advantage of the two kinds of technologies, reducing the construction cost of the CDN as well as promoting the effective supervision of the P2P, so it gives us a brand new view of building the audio and video public network platform.