The detection of far-field weak target is influenced by the strong near-field platform radiated noise interference in the towed line array sonar.The near-field sound is with multiple channel propagation

and the far-field sound is with plane wave propagation.By these propagation characteristics

the matched field processing technology and the direction of arrival estimation technology are combined together.The spatial matrix filters are designed by the near-filed platform noise copy vector and the far-field plane wave bearing vector.Two optimization programs are built to achieve different platform noise suppression effects.The optimal solutions are deduced directly and their relationships are established.In the bearing course

the strong interferences exist without filtering

and the blind areas exist after filtering by the spatial matrix filter.The reason is that there are relativities between the platform copy vector and the plane wave bearing vector.Simulations indicate that it can achieve less blind area and higher detection capability with spatial matrix filter processing.