The invention discloses a method for preparing 2,5-furandicarboxylicacid. The method comprises the steps that a reaction substrate and a catalyst are added in a system, wherein the reaction system iscomposed of water and a biomass-base solvent; in a certain of oxidizing atmosphere, the product 2,5-furandicarboxylicacid is obtained through high-temperature hydrolysis, isomerization, dehydration and oxidization, wherein the biomass-base solvent is one or two or more of gamma-valerolactone, ethyl acetate and methyl levulinate; the reaction substrate is one or two or more of cellulose, cellobiose, glucose and fructose; the catalyst is one or two or more of Ru / C, Pt / C, Pd / C, Rh / C, Cu / C, Ni / C and Co / C; the oxidizing atmosphere is one or two of oxygen and air. In the method, the water and the biomass-base solvent serve as reaction media, the reaction efficiency is high, the water and the biomass-base solvent do not interfere with each other, the product is helped to be obtained through recrystallization, and a good idea and method are provided for preparing common chemicals. The preparation process is environmentally friendly, and the method is environmentally friendly and high in operability.