Abstract: The passive detection and location of the underwater target can be realized by using a single three-axis seismic sensor. In order to increase the resolving capacity in merely using the condition of only deploying single Ocean Bottom Seismometer (OBS), the MUSIC algorithm is introduced into DOA (Direction Of Arrival) estimation. To address the performance degradation caused by the traditional MUSIC algorithm existing in the coherent signal source, the oblique projection polarization separation method is employed to separate multi-path propagating signal which gives the high resolution DOA estimation in various subspace of polarization state based on the estimate to spatial spectrum of the target in water. The simulation results show that the proposed of this algorithm achieves high resolution DOA estimation with only one OBS in shallow water multi-path environment. The experimental results using data collected in lake demonstrate the effectiveness of proposed algorithm.