Abstract: A centroid localization algorithm (CLA) for wireless sensor networks is presented based on power control (CLAPC). In this algorithm, the target area is divided into a series of grid cells by using discrete power control method, thus each intersection formed by these cells would be a minimal zone including the unknown nodes. As a result, CLAPC can enhance the energy efficiency of the network system and improve the precision of localization. The algorithm proposed in this paper is anchor-free localization and flexible in practice. The validity of CLAPC is evaluated and confirmed through extensive simulations.