Abstract: In the presence of complex high-power electromagnetic fields, energy selective surfaces (ESS) often struggle to simultaneously protect against both transverse electric (TE) polarized waves and transverse magnetic (TM) polarized waves. The main goal of this study is to design a polarization insensitive ESS for high-power microwave shielding. The unit-cell of the designed ESS consists of four split resonance rings (SRR) connected with four PIN diodes and a cross shaped (CS) composite structure and a FR-4 dielectric layer. Based on full electromagnetic wave and equivalent circuit model analysis, the composite structure parameters are optimized and the transmission characteristics are analyzed. Simulation results show that the proposed ESS exhibits insertion loss of less than 1 dB and shielding effectiveness (SE) of more than 20 dB in the operating frequency band. The working mechanism of the ESS was analyzed in detail by means of surface electric field, current distribution, and simulated spatial electric field. The electromagnetic simulations were conducted to investigate the effects of different structural parameters and oblique incident angles with different polarization on transmission performance. The results show that the ESS exhibits excellent polarization insensitivity and wide angular stability under the incidence of TE polarized waves and TM polarized waves. In addition, the prepared samples were tested by the waveguide test method, and the measurement results were found to be in good agreement with the simu-lation results. The proposed dual-polarization protected ESS structure has significant application potentials in the field of high-power microwave and radome protection.