Abstract: A method for preparing a universal microbial medium by eutectic system-based cellulose liquefaction. The method includes: 1) mixing ionic liquid and cellulose, where the ionic liquid is preheated; 2) mixing a mixed solution I obtained in step 1) and distilled water; 3) filtering a mixed solution II obtained in step 2); and 4) diluting a filtrate obtained in step 3) with the distilled water to obtain the carbon source. A medium prepared from the carbon source can be used for culturing various microorganisms, with a desirable growth state of the microorganisms.