Localization is an important topic in wireless sensor networks because sensor nodes are randomly scattered over a region and they get connected into network on their own. Adjusting transmission power levels has an important impact on energy efficiency and network lifetime in wireless sensor networks. In this work, we proposed a localization scheme with power control in a wireless sensor network. Each node can transmit beacon packet in different power levels. Whenever a node receives beacon packets transferred in different power levels, it will adaptively select beacon packet to estimate distance to the landmark. When a sensor node has estimated the distances to three landmarks, it can compute its location by triangulation. Simulation results show that the proposed scheme can improve the error rate of localization.