The invention provides a method of improving luminous efficiency of a rare earth-doped up-conversion luminescence nanometer material through changing the usage of a ligand. According to the method, the synthesis adopts a hydrothermal-solvothermal method, an organic ligand is an organic compound such as monocarboxylic acid, dicarboxylic acid or polycarboxylic acid, and amine, the molar ratio of rare earth ions to the ligand is 2:1-1:100, the molar ratio of NaOH to the ligand is 0:1-1:1, water/alcohol, water/n-propanol alcohol, water/isopropyl alcohol, water/n-butyl alcohol, water/acetone or water/ethylene glycol is used as a solvent, the temperature ranges from 180-240 DEG C, the reaction time is 2-24h, and the F<->/Re value ranges from 4-12. With the method, the problems of selecting various ligands for synthesizing the up-conversion luminescence nanometer material, improving the luminous efficiency of the rare earth-doped up-conversion luminescence nanometer material, synthesizing the water-soluble up-conversion luminescence nanometer material, and the like can be mainly solved.