The invention disclose a filter paper impregnating emulsion in the automotive industry and a method for modifying the filter paper impregnating emulsion by using a polymeric emulsifier, and relates to a filter paper water-soluble impregnated resin in the automotive industry and the method for modifying the filter paper impregnating emulsion in the automotive industry by using the polymeric emulsifier. The emulsion of the invention comprises the polymeric emulsifier of 0.5 percent to 4 percent, a general emulsifier of 0 to 3 percent, hard-monomer styrene of 40 percent to 55 percent, soft-monomer acrylic ester of 40 percent to 55 percent, crosslinking monomer of 2 percent to 5 percent, and functional monomer of 2 percent to 10 percent according to the mixture ratio of the mass percent. The invention has the modification method that: the hard-monomer, the soft-monomer, the crosslinking monomer and the functional monomer are used as a copolymer, and the automobile air filter paper water-soluble impregnated resin is synthetized through a semicontinuous pre-emulsification emulsion polymerization method. The invention greatly enhances the hydrolytic resistance, solvent resistance and strength character of the filter paper after the impregnating in the water-soluble resin, lowers the emulsion manufacturing cost, and reduces the environment pollution caused by dissociative emulsifier after the general emulsion is applied. The invention has the advantages of high monomer percent conversion, stable emulsion, etc.