The invention discloses a preparation method of a polyacrylonitrile carbon fiber/a phenolic resin composite material engine cover for automobiles. The preparation method comprises the following stepsof 1, mixing and stirring phenolic resin and carbon powder; 2, impregnating polyacrylonitrile carbon fiber in resin mixed solution and airing; 3, pressing and molding; 4, carrying out resin dipping treatment; 5, curing treatment; and 6, carrying out machining and grinding and forming, so as to prepare the polyacrylonitrile carbon fiber/a phenolic resin composite material cover for the automobiles.According to the preparation method of the polyacrylonitrile carbon fiber/the phenolic resin composite material engine cover for automobiles, the polyacrylonitrile carbon fiber/the phenolic resin composite material structure is adopted, the prepared polyacrylonitrile carbon fiber/the phenolic resin composite material engine cover for automobiles has the advantages of low density, excellent mechanical property, high mechanical strength, fatigue resistance, corrosion resistance, vibration reduction, insulativity, good impact toughness and the like, the problems that an existing engine cover istoo high in rigidity, too large in brittleness and not beneficial to pedestrian protection are solved, and the structure is simple.