Since the traditional localization algorithm of wireless sensor networks,namely the DV- Hop algorithmwithout distance measurement,is of low accuracy due to the imprecise estimated distance,a new one based on theclassification of distance estimation methods is proposed.In this algorithm,the concept of optimal auxiliary anchoris introduced to improve the accuracy of distance estimation.During the estimation,unknown nodes find the opti-mal auxiliary anchor in light of the requirements of distance estimation at the beginning，and then estimate the dis-tance according to the types of the estimation methods.Moreover,in order to further improve the localization accu-racy,a“nonlinearity- hop number”weighting factor is introduced in the trilateral localization and the expectation ofestimated coordinate of unknown nodes is finally obtained.Simulated results demonstrate that the proposed localiza-tion algorithm greatly improves the accuracy of distance estimation only with an appropriate increment of communi-cation cost.