Abstract: Hβ-Al₂O₃ composite supports were prepared through mechanically mixing Al₂O₃ with hierarchically mesoporous Hβ zeolite obtained by desilication with NaOH solution; bifunctional NiWP/Hβ-Al₂O₃ catalysts were then obtained by impregnation method. The composite supports and NiWP/Hβ-Al₂O₃ catalysts were characterized by XRD, BET and NH₃-TPD; the effect of Hβ addition on the catalytic performance of NiWP/Hβ-Al₂O₃ in diesel oil hydro-upgrading was investigated in a fixed bed reactor with fluid catalytic cracking (FCC) diesel as the feed. The results showed that by adding 15% Hβ in the Hβ-Al₂O₃ composite support, NiWP/Hβ-Al₂O₃ catalyst performs best in diesel oil hydro-upgrading; under 360 ℃, 8 MPa, volume space velocity of 1.0 h^-1 and volumetric hydrogen/oil ratio of 800, the desulfurization degree reaches 99.77%, the density of FCC diesel oil is decreased from 0.927 to 0.837 g/cm³, while the cetane value is increased from 13.78 to 55.39.