The invention discloses a preparation method of a NiF2/AlF3 catalyst. The method comprises the following steps: blending Al(NO3)3.9H2O and PO-EO, adding ammonia water until the PH value is equal to 8.8-9.2, aging for 3-4h, carrying out suction filtration under the reduced pressure, drying, and calcining to obtain an Al2O3 catalyst; dissolving Ni(NO3)2.9H2O in distilled water, then dipping into gamma-Al2O3, drying, calcining for 4-5h at 450-470 DEG C in the air atmosphere to obtain a NiO-Al2O3 catalyst; molding the NiO-Al2O3 catalyst by tabletting, putting the product in a fixed bed reactor, introducing mixed gas of HF and N2, carrying out fluorination for 1.5-2.5h at 245-255 DEG C, then carrying out fluorination for 4-5h at 370-390 DEG C, and cooling. The NiF2/AlF3 catalyst prepared by themethod is good in stability when being used for a dehydrofluorination reaction by using CF3CFH2.