Abstract: A polarization filtering scheme is employed to resolve interference from GSM base station to the radar in practice. By analyzing the existing Auto Polarization Cancellation (APC) algorithm, a new filtering algorithm based on the optimal reception of partially polarized signal is proposed. The polarization Stokes vector of GSM signal is estimated, and then the optimal receptive polarization is calculated on the principle of the minimum interference power. The effectiveness of polarization filter is finally validated by the experiment of interference suppression. Compared with the existing algorithm, the proposed method not only achieves good performance in anti-interference, but needs shorter time in weight convergence, and it is more stable as well.