Abstract: In this paper, a method of using passive directional buoys array to locate and track underwater maneuvering targets is studied and a specific implementation of the positioning and tracking filter is proposed by applying Kalman filtering (KF) principle. This method can integrate the current and past error measurement data of multiple buoys to improve the positioning accuracy and continuously output the estimation of underwater target motion parameters to lock the target motion trajectory. The key to realize this method is to establish a mathematical iterative operation model of the underwater target and buoys array, including dynamic and observation processes of state space. Since passive directional buoy array tracking is a nonlinear estimation problem, and the Kalman filter is linear, an approximate linear observation equation to apply the Kalman filter to solve the problem is designed in this paper. The tracking effect of the filter is studied by computer simulation, and by comparison, the estimation accuracy is significantly higher than that of the least square method. Furthermore, simulation results show that the filter can adaptively track the unsteady motion process of the target. The method has certain application prospect and guiding significance in engineering practice.