Abstract: A mediation-based dynamic coalition task allocation scheme for single target tracking in wireless sensor networks is presented,which simplifies the negotiating process of coalition in the present scheme.Success ratio of the coalition formation is increased.A coalition member updating scheme is introduced to realize dynamic task allocation.The energy consumption is reduced and the performance of the network is improved as well.The mediation-based dynamic coalition task allocation scheme is compared with the case-based reasoning one in simulations,and the result demonstrates that the former one is advantageous in energy consumptions and tracking quality.