Network’s life cycle and the energy expending rates of mote are important performance criterions for wireless sensor networks (WSN). An improved routing protocol based on LEACH was proposed in this paper to prolong the network’s life cycle. The improved routing protocol took the circumstance into consideration, that is every mote knows the location information of its own and that of the base station. We analyzed that how to use these location information to extend the mote’s life cycle. And then the extension of the entire network life cycle was achieved. Simulation on the NS2-environment was conducted. And the experimental results show that the whole network’s life cycle was extended greatly.