Abstract: With radar jamming evolving toward integration, distribution, and intelligentization, traditional anti-jamming techniques face increasingly severe challenges. Employing multi-domain diversity to expand the dimensionality of radar perception information has become an important development trend in the field of radar anti-jamming. Aiming at the scenario of distributed multi-polarized jamming, an anti-jamming approach using fully polarimetric-arrays with joint polarization-space beamforming is proposed, and the correlation between the output signal-to-interference-plus-noise ratio and the polarization-space state differences between targets and jammers is analyzed in this paper. To quantitatively characterize the impact of state similarity between jammers and targets on joint beamforming performance, a concept of L-loss polarization state domain is proposed. Simulation experiments results demonstrate that the joint polarization-space beamforming algorithm can effectively suppresses two kinds of distributed multi-polarized jamming incident via the mainlobe: one is composite escort + support jamming, and the other is self-protection + support jamming with distinct polarization states. The proposed L-loss polarization state domain can effectively depict feasible polarization states under given processing loss constraints, which provides theoretical basis and reference for mainlobe anti-jamming design and performance evaluation of polarization-sensitive array radars.