Based on the theory of polarization filtering and the merits of interference suppressions when adopting oblique projections, a novel polarization filtering algorithm is proposed in this paper. The proposed method can effectively separate the target signal and interference without additional transformation and compensation processing, and the target does not suffer distortions after separation. The suggested scheme is still valid when the target and interference hold the same polarized angle but different phase difference in polarized angle. We extend the application to the scope of known target polarization but unknown interference polarization, finding that the interference is restrained and the amplitude/phase of the target are both totally kept. Theoretic analysis and mathematical deduction show that the proposed scheme is a valid and simple implementation. Simulation results also demonstrate that the suggested method can obtain better filtering performance than the conventional polarization filtering (CPF) and the null-phase-shift polarization filtering (NPSPF). It is proved that the proposed OPPF is an extension to the CPF and the NPSPF, and it develops the theory of polarization filtering effectively. Based on the theory of polarization filtering and the merits of interference suppressions when adopting oblique projections, a novel polarization filtering algorithm is proposed in this paper. The proposed method can effectively separate the target signal and interference without additional transformation and compensation processing, and the target does not suffer distortions after separation. The suggested scheme is still valid when the target and interference hold the same polarized angle but different phase difference in polarized angle. We extend the application to the scope of known target polarization but unknown interference polarization, finding that the interference is restrained and the amplitude / phase of the target are both totally kept. Theoretic analysis and mathematical deduction show that the proposed scheme is a valid and simple implementation. Simulation results also demonstrate that the suggested method can obtain better filtering performance than the conventional pol a filtering (CPF) and the null-phase-shift polarization filtering (NPSPF). It is demonstrated that the proposed OPPF is an extension to the CPF and the NPSPF, and it develops the theory of polarization filtering effectively.