Abstract: An Energy Selective Surface（ESS）was presented to manage the conflicting requirement for shielding protection from high-power electromagnetic pulses（EMPs）and normal transmission of signals， as it can isolate high-power EMPs but allow the device to send and receive signals normally. Using the variable impedance surface theory，the protection mechanism of the ESS was investigated. As the energy selective characteristics offered by diode impedance could be controlled by high power microwave，we designed an ESS made of a diode array to provide protection from the effects of linear polarized EMPs. The performance of the designed ESS had been simulated and tested. Results show that insertion loss of the proposed ESS to normal signals is less than 2 dB，and isolation to intense EMPs is more than 20 dB. Therefore the energy low-pass performance is achieved