Abstract: The problem of node localization of wireless sensor networks was concerned expecially because it is related to many actual applications. There are two kinds of algorithm of node localization of wireless sensor networks,namely range-based and range-free. On the basis of analysis of disadvantages of range-based algorithm,the paper researched the improvement of localization of range-free emphatically. It also expanded typical centroid algorithm and gave performance evaluation of centroid algorithin by experiment.