The invention discloses a preparation method of a dry strength agent for fine dried noodle cardboard paper. The dry strength agent comprises the following raw materials in parts by weight: 10 to 15 parts of modified starch, 10 to 15 parts of polyacrylamide, 30 to 40 parts of acrylic acid emulsion, 15 to 20 parts of nanometer silicon dioxide, 1 to 5 parts of citric acid, 1 to 5 parts of sodium dodecyl sulfate, 1 to 5 parts of phospholipid and 4 to 8 parts of stearamide. The dry strength agent is simple in components, simple in preparation method and suitable for the fine dried noodle cardboardpaper; the acrylic acid emulsion serves as a main raw material and the nanometer silicon dioxide is added, so that the strength of the dry strength agent is enhanced; the polyacrylamide is added and can form a cladding layer on the surface of the nanometer silicon dioxide, so that the combining capacity with fibers is improved; meanwhile, the modified starch is added, so that adhesion degree of fiber pulp is increased, the modified starch can be dispersed in the fiber pulp rapidly and the hardness of the fiber pulp is enhanced.