Abstract: Power management is an important technique to prolong the lifetime of battery-powered wireless Ad Hoc networks. This paper analyzes the Power Saving Mechanism (PSM) of IEEE 802.11 Distributed Coordination Function (DCF) and presents a self-adaptive power saving mechanism, which consists of three different beacon intervals. In the new scheme the node selects one of the three beacon intervals dynamically, depending on its traffic. Simulation results show that the new scheme not only improves the efficiency of energy greatly but also achieves desirable transmission delay and throughput.