The invention discloses a blue fluorescence chiral organic dye molecule as well as a preparation method and the application of the blue fluorescence chiral organic dye molecule. The chiral organic dye molecule comprises a left-handed (M) screw type optical activity enantiomer and a right-handed (P) screw type optical activity enantiomer, the structural formulas of the left-handed (M) screw type optical activity enantiomer and the right-handed (P) screw type optical activity enantiomer are shown in the formulas (M)-1 and (P)-1, Ar in the formula (M)-1 or (P)-1 is chosen from a phenyl group or a replaced phenyl group, and the replaced phenyl group is chosen from at least one of 4-methylphenyl, 4-methoxy phenyl, 4-fluoro-phenyl, and 4-cyano-phenyl. The chiral organic dye molecule forms a twisting structure in a way that an aromatic diester attracting an electron and a dinaphthalene derivative are connected by a 6-membered ring through methylene, moreover, the chiral organic dye molecule also has a certain spiroconjugated compound; after the extra aromatic substituent group is introduced, the fluorescence emission is promoted, the structure is more twisted, then the excitation wavelength and the emission wavelength are relatively short, taking Ar serving as the phenyl group for an example, the excitation wavelength in the tetrahydrofuran is 344 nm, the emission wavelength is 439 nm, and the Ar shows approximately pure blue color in a solution.