Method for improving quality of bio-oil

The invention relates to a method for improving quality of bio-oil, relating to bio-oil. Bio-oil, acetic anhydride and solid alkali are mixed and heated for backflow, preparing catalytically upgraded bio-oil; and distilling the catalytically upgraded bio-oil under the atmospheric pressure, removing distillate under 120 DEG C, and collecting distillate of 120-250 DEG C, thereby obtaining refined bio-oil. No alcohol is needed, only a small amount of glycoside carboxylate needs to be added, and the quality of the bio-oil can be improved via catalysis. The stability of the refined bio-oil can be improved greatly.