Alkali-free glass fiber filter material is a filter material with excellent alkali resistance made of alkali-free glass fiber twisted yarn formed by chemical treatment of glass fiber yarn before weaving. When encountering alkaline gas in the equipment room, the alkali-free glass fiber filter material itself does not have alkali resistance and is easily corroded by the gas. At this time, the alkali-free glass fiber cloth woven from the alkali-free glass fiber yarn with alkali resistance can fully adapt to the alkali flue gas filtration without the filter material corrosion phenomenon.