MANET routing model based on P2P has become a hot topic recently，but the research results have been mainly applied to small or medium MANET, without fully using of the advantages of P2P distributed share theory. As a result, there exist detour and inefficient problems. In light of this, a large-scale MANET layered share routing model based on P2P is presented. It introduces layered mechanism based on network physical topology to enhance network scalability on the basis of cross-layer optimization, expands P2P distributed share strategy into MANET Routing layer, and can solve the detour problem in the previous algorithm. The simulation experiment shows that this new routing model can greatly increase the MANET routing efficiency.