The invention provides a kind of machine air filter paper. The machine air filter paper comprises a piece of body paper and an impregnant used for impregnating the body paper, wherein the body paper uses the following fibers in parts by weight: 30-50 parts of high-density cotton linter pulp, 5-12 parts of polypropylene fibers, 20-40 parts of chopped alkali-free glass fibers and 3-8 parts of ceramic fibers, and 0.1-4 parts of amphoteric polyacrylamide, 0.2-0.8 part of modified starch and light calcium carbonate, 0.5-5 parts of polyoxyethylene with the molecular weight of 2.5-3 millions and 0-0.2 part of a defoaming agent are used in preparation of the body paper; and the impregnant includes modified phenolic resin, modified nano titanium dioxide polytetrafluoroethylene emulsion and stearic acid modification liquid. The machine air filter paper provided by the invention has the advantages that the obtained machine air filter paper is greatly improved in water resistance, temperature tolerance, non-viscosity, acid and alkali resistance, corrosion resistance, wear resistance, strength and deformation resistance by virtue of a formula of the body paper and three times of impregnating and can be cleaned and used repeatedly, and hydrophobic and oleophilic functions are increased, so that the machine air filter paper can be used for oil-water separation.