The invention belongs to the field of material science, and provides a preparation method of NaREF4 solid spherical particles. The method has the technical scheme that the method comprises the following steps of uniformly mixing nitric acid compound of rare earth element and ethylene diamine tetraacetic acid in deionized water; preparing a solution with the rare earth element concentration being 0.01 to 0.20 mol/L; adding ammonium fluoride solution during stirring; introducing F<-> ions to obtain turbid liquid; transferring turbid liquid into a reaction kettle; performing hydrothermal reactionfor 12 to 48h at 100 to 200 DEG C; performing centrifugal separation on reaction products; performing cleaning and drying to obtain white powder particles NaREF4 (RE=La-Lu, Y). The technical scheme is simple; the implementation is easy; the NaREF4 monodisperse nanometer solid spherical particles can be easily obtained.