Abstract: The localization of Wireless Sensor Network (WSN) is an optimization problem of measurement based on different distance or path in essence. To improve the localization accuracy of WSN node, a novel algorithm named Gravitational Search Algorithm (GSA) for node localization in Wireless Sensor Network (WSN) is proposed. The algorithm uses the information received by the unknown nodes from the anchor nodes and searches the location of unknown nodes by means of the iterative method. Compared with its counterparts, the simulation results show that the proposed method could not only improve its localization accuracy but only effectively suppress the influence of range error on the localization error and then the localization accuracy of sensor nodes with range error and range-free error is greatly improved.