The invention relates to a fluorine nanometer composite modified anticorrosion paint, comprising 32 to 55 parts of waterborne polyurethane emulsion, 28 to 43 parts of epoxy resin, 8 to 15 parts of modified nanometer titanium dioxide, 11 to 19 parts of fluorine polymer, 7 to 14 parts of pigment, 0.3 to 0.8 part of a catalyst triethylamine and 12 to 17 parts of an auxiliary agent. A preparation method for the paint comprises the following steps: step 1, preparing modified nanometer titanium dioxide; step 2, preparation of a fluorine polymer; and step 3, compounding of the anticorrosion paint. According to the invention, the volume-filling density of a carrier is improved through nanometer titanium dioxide, so capillary action is reduced and shielding density is greatly improved; a film structure can be filled with tiny particles of a nano-material, so the density of a film is enhanced, permeability of the film is reduced, and corrosion of water, oxygen and the like to a metal substrate is efficiently blocked; thus, the anticorrosion performance of the paint is improved.