Radio frequency fingerprint (RFF) is a mature physical-layer identification technique for specific emitter identifi-cation (SEI). However, RFF faces the problem of low discrepancy. Therefore we propose polarization fingerprint (PF). PF has frequency characteristics derived from antenna hardware im-perfections and spatial characteristics derived from the vectorial properties of polarization. Based on these two characteristics, the mathematical model of PF is constructed. Because the spatial characteristics are not limited by the improvement of hardware manufacturing process, it still has a significant discrepancy. We also propose a spatial polarization compensation (SPC) for PF changes due to emitter movement. With spatial characteristics and SPC, PF can be effectively applied to SEI. However, the spatial characteristics also bring a trade-off between the identi-fication accuracy and the maximum emitter capacity. Finally, these two characteristics of PF and the proposed SPC are experimentally verified, then the identification accuracy of the proposed method is measured in real scenarios.