Node localization is one of the core technologies in wireless sensor network（WSN）. Different localization methods have different effects on localization results. In response to the deficiency in accuracy of localization during the process of searching for the unknown node localization with the least-square algorithm, a localization algorithm is proposed based on improved cuckoo search（CS） algorithm. The first step is to establish the mathematical model according to the optimization objective, and then we design the fitness function of cuckoo search algorithm. Finally, we modify the parameters of the step length and rejection probability and thus determine the coordinate position of the unknown nodes quickly. The simulation results show that the proposed algorithm is better than the distance vector hop(DV-HOP) and the self-adaption cuckoo search and distance vector hop(SACSDV-HOP) algorithms. The algorithm can effectively reduce the error of localization in WSN and improve the accuracy in locating nodes. Accordingly, it has high practicability in WSN node localization.