The present invention relates to a method for preparation of organofluoro compounds containing radioactive isotope fluorine-18. More particularly, the present invention relates to a method for preparation of organofluoro compound [.sup.18F]florbetaben or [.sup.18F]AV-45 having and , respectively, by reacting fluorine salt containing radioactive isotope fluorine-18 with alkyl halide or alkyl sulfonate in the presence of alcohol of Chemistry Formula 1 as a solvent to obtain high yield of organofluoro compound. Synthesis reaction according to the present invention may be carried out under mild condition to give high yield of the organofluoro compounds and the reaction time is decreased, and thereby is suitable for the mass production of the organofluoro compounds.