With the popularity of P2P software, P2P has become critical applications affecting Internet network structure. In the long distance backbone networks of China ISP, P2P traffic accounts for more than half, not only to bring the huge pressure for ISP, also make the network congestion increasingly serious. So this paper puts forward an optimization scheme for agreement BT. With compositing cooperation of users and analog the topology structure of bottom network, it has no impact on the performance. And it guides traffic more happened in local networks, so that reduce the P2P traffic between networks. The tests show that the system can not only as far as possible to achieve the purpose of the whole optimization by traffic localization, and more can enhance the performance of the user system.