Abstract: An ensemble Kalman filter (EnKF) approach is proposed for performing sequential tracking water column sound speed profile (SSP) using a moving acoustic source. Firstly, the SSPs are discretized in depth and range. Then, the SSPs are expressed by the empirical orthogonal functions (EOFs). Secondly, the acoustic source state information and the first three orders of EOF coefficients are expressed as state variable, and the acoustic field information received by vertical line array are the measured values. Successively, the state variables and measured values are used to establish the state-measure model. Lastly~EnKF is used to tracking the state variables. The simulation results show that the root mean square error and absolute error is very small, so the acoustic source tracking-positioning has a high accuracy. Moreover, increase the number of sample collection, increase the signal-to-noise ratio and increase the number of receiving arrays can improve the tracking-positioning results. The method is verified using the experimental data of the East China Sea.