Abstract: In this paper, the principle and mechanism of NS2 were analyzed. The split object model and discrete-event dispatch were emphasized, taking sensor network as a key, the extension mechanism of sensor network for NS2 was discussed,including energy consumption model,mobile node extension and routing protocol. Based on these works,the code transferring process and simulation model of wireless sensor networks routing protocol in NS2 were introduced. Then taking LEACH as an example, some simulation experiments were carried out. The network simulation and codes extension in NS2 become easily by the help of such works.

Key words: NS2 , Wireless sensor networks, Protocol extension, Simulation, LEACH