The invention discloses a ketone-group-containing aqueous polyurethane resin and a preparation method thereof. The ketone-group-containing aqueous polyurethane resin consists of the following components in part by weight: 55 to 80 parts of diisocyanate, 105 to 150 parts of polyester diol, 18 to 45 parts of hydroxyketone, 15 to 20 parts of dimethylolpropionic acid, 10 to 15 parts of triethylamine,40 to 55 parts of acetone, 18 to 26 parts of adipic dihydrazide and 600 to 900 parts of deionized water. The preparation method comprises the steps of the preparation of a resin, the dispersion and emulsification of the resin in the deionized water, and the removal of the acetone in an aqueous resin. In the ketone-group-containing aqueous polyurethane resin, the crosslinking and curing of ketone groups (keto carbonyl groups) and the adipic dihydrazide can be performed when water is volatized and the resin forms film at room temperature; and a cured substance has good water resistance and alcohol resistance, and higher hardness. The water resistance and the alcohol resistance of the cured substance reach HG/T3828-2006 standard for 'Aqueous Coatings for Indoor Woodenware'. The hardness (scratch) reaches 2H.