An ad hoc network is a dynamically wireless mobile network. It can construct network automatically and quickly. Because of the importance and universality of application, ad hoc network is trend to become a research hotspot. It is necessary to research an effective routing protocol so as to be adapted to mobility of terminal equipment and to provide the reliable data transmission. This paper firstly studied and analyzed existed routing protocols, and simulated these protocols. Finally we proposed an improved routing protocol based on DSR and AODV, in which we divided all nodes into different clusters, and every cluster has only one cluster head. These nodes within the same cluster communicate using DSR protocol while those nodes in the different cluster communicate through the cluster head using AODV protocol. So, the data packet can go through the shortest link, thus it can decrease transmission delay and reduce energy consumption remarkably. Finally we use the network simulation software named NS2 to simulate experiment result. The results show that this protocol can improve the performance and the service quality of the network.