The study indicated that yttrium(III) could form an ion association compound with a new synthetic reagent, 1,6-bi(1'-phenyl-3'-methyl-5'-pyrazolone-4'-)hexanedione (BPMPHD) and cetyl trimethyl ammonium bromide (CTMAB). The compound could enhance the natural fluorescence of BPMPHD by about 260 times, upon which a new fluorescence method was developed for determining yttrium in rare earth (RE) samples. The determination range was 9-900 ng/ml. The detection limit was 1.8 ng/ml. The composition of the ion association was [Y(BPMHD)(2)](-)CTMAB(+).