As the parameter setting, available power control algorithms for readers exist uncertain random backoff and insufficient in this paper presents an improved distributed power control algorithm marked as EDPC. In this algorithm, the working time sequence of the reader is reasonably set and the selection mechanism of working time slot is improved, thus increasing the efficiency and reliability of power control. Simulated results indicate that, as compared with the existing DAPC and PPC algorithms, the proposed algorithm enlarges the detection range of the reader, shortens the detection time, and improves the integrated performance of the reader system.