The invention discloses a method for preparing a test paper for rapidly determining dairy cows subclinical ketosis, which comprises the following steps of: adding boric acid, aminoacetic acid and ethylene diamine tetraacetic acid solution in Arabic gum dissolved in a hot-water bath, adjusting the pH value of the prepared solution to be 7.0, soaking the test paper for 20 minutes in the prepared solution while the prepared solution is hot, drying the test paper in a drying oven at 60 DEG C, and standing the test paper in the drying oven overnight; and dissolving ethylene glycol, sodium nitroprusside and absolute ethyl alcohol in the hot-water bath, soaking the test paper for 20 minutes in the prepared solution while the prepared solution is hot, taking the test paper out, blotting moisture in the test paper by using filter paper, drying the test paper in the drying oven at 60 DEG C, and standing the test paper in the drying oven overnight so as to obtain the test paper. The reagent strip takes the concentration of beta-hydroxybutyric acid in blood more than 1.2mmol/L as a positive criteria; and the production practice proves that the reagent strip has the advantages of low cost, simple and easy operation, quick response, high specificity and high sensitivity, can be used for various determined samples such as blood, urine, serum, plasma and milk, and has wide application scope.