The modified weighted centroid location algorithm applying to outdoor is proposed. The algorithm analyses the measure principle of Received Signal Strength Indication (RSSI), in the case of unknown path decline index, which can convert the distance relation to the received power relations. In addition, the RSSI measure distance is obtained by the Gauss filtering, and the inverse is used as the weighting factor of the modified weighted centroid localization. The weighted centroid algorithm discusses the impact on the precision resulting from the adjustment coefficient. The ideal correction factor of the outdoor environment is obtained through the comparative analysis. The simulation experiments show that the best location accuracy of the improved algorithm is 0.5190m enough to meet the actual location demand when the dynamic adjustment coefficient is 4.