Aiming at the failure of two-dimensional polarization filtering when the distance between the interference and the signal in the Poincare is too short, a three-dimension polarization filtering approach based on orthogonal projection is proposed in this paper.The algorithm redefines the problem on the basis of traditional methods, a pair of complete orthogonal basis in interference orthogonal subspace is obtained under the interference suppression rule, and the pair of basis has clear physical significance, which facilitates the algorithm's expansion. In the solved subspace, the optimal weights are achieved under the rule. The theory and simulation results indicate that the proposed method can effectively suppress the polarized interference, the performance of traditional algorithm is improved.