The invention discloses a method for preparing fructose from glucose. According to the method, in the presence of an acid catalyst and low carbon alcohol, glucose undergoes an isomerization reaction in a closed high-pressure environment so as to prepare fructose, wherein the acid catalyst is one or more ingredients selected from a group consisting of tungsten salt, aluminium salt, chromium salt, phosphotungstic acid and silicotungstic acid. The method has advantages of mild condition, simple process and high conversion efficiency.