Abstract: Strong directional interference severely affects the weak targets detection capability of the passive sonar. In this paper, a method to suppress the strong directional interference combining blind source separation with beamforming is proposed. It uses the method of sub-band decomposition to realize the broadband interference suppression. The subband array signals are separated by the frequency domain blind source separation algorithm and the bearings of the separated signals are estimated. And if the bearings of the separated signals matching the corresponding signals are set to zeros. Then, it uses the estimated demixing matrixes and the separated signals which were clustered to reconstruct the array domain signal. Finally, the spatial power spectrum and targets bearings are estimated by the beamforming technology. Simulator and sea trial datasets are used to verify the proposed method, and the results show that the proposed method has two decibel gain and six decibel background decrease. It is proved to be effective in the aspects of strong directional interference suppression.