Call Admission Control (CAC) mechanism can protect the existing flows from being disturbed by the newly added flows, which can ensure the quality of service (QoS) of Mobile Ad hoc Networks (MANET). We proposed a routing mechanism with distributed CAC algorithms for MANET based on IEEE802.11e EDCA MAC protocol. A new flow can be admitted by the network only if it can find a path to sustain its traffic. The nodes calculate the available bandwidth according to the local channel state and the information of their neighbor nodes by receiving their messages passively. The distributed admission control routing mechanism is proposed based on the link available bandwidth and the influences on the neighbor nodes by assuming admitting the new flow. Simulations show that our distributed link available bandwidth estimation performs well under different node densities, and with our distributed CAC algorithm, the existing flows can be well protected in multi-hop MANET; the newly added flows can make good use of the bandwidth resources without affecting the neighbor flows.