Polarization estimation of interference signal is crucial for adaptive polarization filters. The filtering effect is restricted by the precision of polarization estimator. Based on the antenna's spatial polarization characteristics of single polarization radar, a new method for polarization state estimation of receiving wave is presented in this paper. Firstly, the principle of the estimation algorithm is introduced. Its performance is analyzed theoretically. Then, corresponding simulation experiment is made to discuss the main factors influencing the algorithm performance and the main approach to improving the performance is given. The validity of this method is demonstrated by theoretical derivation and computer simulation result.