The present disclosure relates to the technical field of chemical engineering, and specifically discloses a method for removing oxygenated compounds from a Fischer-Tropsch oil having a high carbon number. A reaction-extraction combined process is used in this method for removing oxygenated compounds from a Fischer-Tropsch oil having a high carbon number, wherein the Fischer-Tropsch oil (C5-C20) is firstly subjected to alkaline washing with an alkaline aqueous solution to convert acidic substances into water-soluble salts. The Fischer-Tropsch oil is subjected to a primary extraction with a carbonate-based extractant to remove alcohols and esters therein, and subsequently subjected to a secondary extraction with propylene carbonate to remove ketones and aldehydes impurities therein, thereby removing oxygenated compounds in the Fischer-Tropsch oil. After extraction, the content of the oxygenated compounds in the Fischer-Tropsch oil may be down to 1-60 ppm, and the yield of oil product may be kept 90% or more.