Abstract: To study the signal source location based on received signal strength measurement, a least squares optimization algorithm was proposed. Firstly, a linear model was established to calculate path loss. Then, the weighted least squares method was introduced. And a recursive weighted least squares optimization method was presented for sensor node location in wireless sensor networks. Finally, the algorithm proposed in this paper with the two algorithms based on RSS was compared. The simulation results show that, the iterative weighted least squares method presented can greatly improve the positioning accuracy.