The invention discloses a three-proofing filtering element, which comprises a metal external barrel, an upper cover plate, a lower cover plate, a metal inner cover, a paper core upper end cover, a paper core lower end cover, a paper core and an activated carbon granule layer. The three-proofing filtering element has a scientific and reasonable overall structure, can efficiently filter particulates and gas smoke through two-stage filtering, is suitable for military installation, refuge places, fire sites and other specific environments, and has excellent resistance to impact, firing pulse and harsh environment. In the first-stage filtering, the paper core, especially fiberglass paper core, is adopted for filtering, thus having the advantages of high filtering precision, low original resistance, high filtering efficiency, high temperature resistance and high pressure resistance, strong chemical resistance, and resistance to mold and moisture. In the second-stage filtering, activated carbon is adopted for filtering, adsorption and conversion, thus having a distinct effect of removing toxic chemicals, fine dust, pollen, pathogenic bacteria, smoke, water molecules, off odor, formaldehyde, VOC organic volatiles and other gases, and the effective rate is up to 99.99995%.