CEDAR protocol is a distributed routing protocol oriented to Quality of Service (QoS) routing in MANET, and bandwidth is the QoS parameter of interest in this protocol. However, the storage and processing overhead of cedar is fairly high because too many kinds of control packets are exchanged between nodes and too much state information needs to be maintained by core nodes. THe routing algorithm depends fully on the link state information known by core nodes. But the link state information may be imprecise, which will result in route failures. In this paper, we present an improved CEDAR protocol, and propose a new efficient method of bandwidth calculation. Simulation results show that the improved CEDAR is efficient in terms of packet delivery ratio and average end-to-end delay.