The invention discloses a method for preparing galactose derivative cationic liposome nanoparticles. Galactose as a raw material is subjected to total acetylation, 1-O-acetyl removal, trichloroacetic imine esterification, glycosylation, azidation and all acetyl removal reactions to obtain an intermediate, the intermediate is subjected to 3,4-O-isopropylidene formation, etherification, isopropylidene removal, reductive amination, quaternary ammonium salinization and reductive ammoniation, tertiary amination and quaternary ammonium salinization reactions, and two series of galactose derivative cationic liposomes with different physical structures are synthesized; after water dispersion, the corresponding cationic liposome nanoparticles are obtained, have the advantages of good stability, moderate particle size and surface charges, low preparation cost and the like, and can meet basic requirements required for nucleic acid drug transporters.