Localization technology is a very important technology in wireless sensor networks（ WSNs）.Approximate point-in-triangulation（ APIT） test algorithm is a common algorithm

in order to improve positioning precision

improvement is carried out on the basis of the algorithm

triangle perpendicular bisector is divided into four or six quarters

through comparing target node signal intensity received by each node

judge which small area is target node located in. By simulation

the improved APIT algorithm can be improved greatly in precision.