Abstract: This paper presented a kind of circular algorithm, according to principles of concentric circles localization algorithm, based on analyzing several common wireless sensor nodes localization algorithm. The circular localization algorithm focuses on the use of certain rules made by the anchor nodes to drawings in order to continuously reduce the unknown node estimation area is taken until the end to get the smallest region containing the unknown nodes. Then, the centroid position in the smallest area is takero as the estimate coordinates of the unknown nodes. I}he compared simulalion experiments between the concentric circles localization algorithm and circular localization algorithm and the improved schemes show that when the anchor nodes proportion increase to 5% , and in the 20*20 square meter simulation scenarios 1000 sensor nodes are deployed and the anchor node density is 5 %，the error of concentric circles localization algorithm is 34. 86%，and the circular localization algorithm is 26. 64%. The improved scheme uses multiple methods of partitioning rings to improve positioning accuracy. The experimental results show that when the anchor node density is 5%，the localization error of the improved algorithm is reduced to 15. 76%.

Key words: Wireless sensor network, Nodc localization, Circular Localization algorithm, Positioning accuracy, Simulation