The polarization of radar antenna vary with scan direction. This phenomenon is called Spatial Polarization Characteristic (SPC) of antenna. Based on the SPC of single polarized antenna, a novel polarization estimation method is established. Comparing with the traditional estimation method, this one has the following advantages: (i) It does not need dual-polarization channels to estimate the signal polarization; (ii) The polarization and angle of arriving (AOA) of a periodic signal can be estimated simultaneously; (iii) The full-polarization pattern of the antenna can be matched automatically during the estimation. The feasibility of this method is proved by simulation.