Wireless sensor network (WSN) has been widely used in various fields.Node localization is one of the most important technologies.According to the characteristics of uniform deployment of nodes along the boundary of narrow and long regions,we propose a range-free localization algorithm based on RSSI——the location regions may be divided into more location sub-areas by a perpendicular bisector of any two beacon nodes next to the target node,determining which one the target node is located by comparing the value of signal strength received,finally,the centroid of which is used as the position coordinates of the target node.Simulation results show that,compared with the Approximate Point-in-Triangulation Test (APIT),it has more division areas of PB-RSSI,lower computable complexity,higher location accuracy,better robustness and lower energy consumption.