Abstract: Aiming at problem that the RSSI localization algorithm is vulnerable to the environment and it has low localization precision in wireless sensor networks, this paper proposed an improved weighted centroid localization correction algorithm based on RSSI. The algorithm estimated roughly the coordinate of unknown node by using RSSI values through maximum likelihood estimation, then it used the coordinate to calculate the approximate distance between the unknown node and the beacon nodes. The algorithm removed the measurement group whose error were large and it got the weighted formula by the theory that the positioning had the least error when the triangle was trilaterally equal and consisted of three beacon nodes which can communicated with the unknown nodes. The algorithm calculated and corrected the coordinate of unknown node with the help of TDOA beacon nodes through weighted centroid localization algorithm. The simulation shows that the algorithm can effectively reduce positioning errors compared with traditional RSSI localization algorithm and it can also improve localization accuracy.