Node localization technology is one of the important supporting technology for wireless sensor network.In most applications,such as object monitor and track, location router, determining the physical positions of sensor nodes is the basic requirements.The paper proposes a localization algorithm for wireless sensor networks base on location information between multiple nodes, The simulation results in paper show that the localization algorithm is effective, the accuracy of the algorithm is high, and its calculation is simple so that suitable for all sizes of WSN. Furthermore, according to this algorithm and the requirements of the medical monitoring system, this paper proposed a reliable and effective structure for wireless sensor networks, and achieved a good result.