The invention belongs to the technical field of biomass energy, and particularly relates to a method for upgrading bio-oil based on decarboxylic reaction of calcium neutralizer and carboxylic acid. The method transforms carboxylic acid in bio-oil to organic carboxylic acid calcium salt by calcium neutralizer, and then performs heat cracking decarboxylic reaction under anaerobic condition to upgrade. The method can efficiently transform carboxylic acid in bio-oil to ketone compound, effectively reduce acid value of bio-oil, significantly improve heat value and heat stability of bio-oil. The method has the advantages of simple upgrading process, environmental-friendly of production process, recycled calcium neutralizer, low moisture of oil product after upgrading, extremely low acid value and high heat, and so on.