In order to maintain the combat effectiveness of the military weaponry and equipment in increasingly complex electromagnetic environment, the protective technologies of high-altitude electromagnetic pulse (HEMP) need to be researched. HEMP has the characteristics of wide radiation range, high intensity and broad frequency band, and has always been a threat to military weaponry and equipment. The characteristics of HEMP and its influence on electronic information system are analyzed, then some suggestions and strategies for HEMP protection are provided. The research could improve the reliability of our military weaponry and equipment in future battlefield.