Security of routing protocols is the most important secure factor in the mobile Ad Hoc networks.AODV protocol is used widely in the Ad Hoc networks for its simplicity and small control overhead

but it does not have any security mechanism.With some potential insecure factors in AODV protocol analyzed

some necessary improvements are made to AODV protocol

including adding attack detection and building up credence mechanism

which would collaboratively guarantee the network security.Simulation results indicate that it can react quickly when some malicious behaviors in the network are detected and effectively protect the network from kinds of attacks.