The invention relates to a method for preparing 3-descarbamoyl-cefuroxime acid. The method comprises the following steps of: (1) dissolving 7-aminocephalosporanic acid (7-ACA) in water or a methanol solution to prepare a 7-ACA solution, and performing hydrolysis reaction to obtain a 3-deacetyl-7-aminocephalosporanic acid (7-DACA) solution; (2) dissolving an acylchlorination reagent in a solvent, adding a cosolvent, adding (Z)-2-methoxyimino-2-(furyl-2-yl)acetic acid ammonium salt (SIMA), reacting, filtering, adding water or performing rotary evaporation to remove the excessive acylchlorination reagent, performing vacuum rotary evaporation, adding a homogenization reagent, and dissolving to obtain a (Z)-2-(furyl-2-yl)-2-(methoxyimino)-acetyl chloride (SMIF-Cl) solution; (3) adding the homogenization reagent into the 7-DACA solution, dripping the SMIF-Cl solution, regulating the pH value, preserving heat and reacting to obtain a reaction solution; and (4) decolorizing the reaction solution, regulating the pH value, adding purified water, growing a crystal, filtering, and performing vacuum drying. Reactants form a homogeneous system by adding the homogenization reagent, so that the contact area of the reactants is expanded, the reaction rate is increased, and reaction time is shortened.