The invention discloses a nano fluorescent material and a dual-mode up-conversion fluorescent anti-counterfeiting material prepared by utilizing the nano fluorescent material, and belongs to the technical field of fluorescent materials. A preparation method of the nano fluorescent material comprises the following steps: (1) dissolving NaOH into deionized water, adding ethanol and oleic acid, and performing uniform stirring to obtain a solution A, wherein 2-6 ml of the deionized water, 5-10 ml of the ethanol, and 8-15 ml of the oleic acid are required per 0.3 g of the NaOH; (2) preparing a TmCl3 aqueous solution with a concentration of 0.5-2 mol/l and a YbCl3 aqueous solution with a concentration of 0.5-2 mol/l, and mixing the TmCl3 aqueous solution and the YbCl3 aqueous solution accordingto a certain ratio to form a solution B; (3) adding the solution B into the solution A, and performing stirring to obtain a mixed solution C; (4) adding 1-3 mmol of NaF into the solution C, and performing stirring to obtain an initial product; and (5) transferring the initial product obtained in the step (4) to an autoclave, performing a reaction at 140-240 DEG C for 100-400 min, performing washing, and performing drying to obtain the nano fluorescent material.