The invention provides a high-strength adhesive for a corrugated paperboard. The high-strength adhesive is prepared from the following raw materials: modified starch, polyvinyl alcohol, vinyl acetate,acrylic acid, a stabilizer, mineral oil, acrylamide, isocyanate, a CP-88 water repellent agent, cellulose, polylactic acid and agar. The preparation method comprises the following steps: carrying outacidolysis oxidation on starch; adjusting the pH value of the obtained modified starch emulsion to 4.5 to 5.5; and adding acrylamide, cellulose and vinyl acetate, heating, adding acrylic acid in a dropwise manner, keeping the temperature, cooling the secondary modified starch emulsion, adjusting the pH value to 6.0-8.0, adding polyvinyl alcohol, a stabilizer, mineral oil, isocyanate and a CP-88 water repellent agent, dispersing, finally adding polylactic acid and agar, and stirring to obtain the product. The prepared adhesive is used for compounding corrugated paperboards so as to significantly improve the strength of the corrugated paperboards.