Abstract: Considering the polarization parameters of target are not usually unknown in Polarization Space Time Adaptive Processing (PSTAP), a new method which filters after estimating polarization state is advanced. The new method is deemed to reduce the computation, because which is not using a filter bank to cover the whole polarization domain. Firstly, the Minimum Variance Unbiased (MVU) estimator and Orthogonal Projection (OP) estimator are developed. Then, the Cramer-Rao Bounds (CRB) for MVU estimation of the target polarization parameters are briefly derived. The performance of MVU estimator is superior to OP estimator. Finally, the new PSTAP method performed significantly better than the traditional optimum space-time processing technology, especially in the case of the target slowly moving. Simulations demonstrate the correctness of models.