Abstract: Aiming at the sharp performance decline of the mobile Ad Hoc network(MANET) because of overloaded data flow,a novel distributed end-to-end admission control mechanism based on passive bandwidth estimation is proposed.The available bandwidth is estimated with the consideration of channel utilization ratio,interframe collision and backoff procedures in a network,and whether the current network capatity satisfies the business requirement is judged by integrating the route finding process from the end-to-end perspective.Simulation results show that the available bandwidth can be estimated accurately by the proposed mechanism,moreover,with the proposed admission control method,the overloaded flow can be rejected effectively,and the average delay and drop ratio of packets are decreased.