Abstract: The catalyst for slurrybed hydrotreating of distillate oil was prepared; the preparation parameters like the loading of active components and phosphorus additive on the hydrotreating performance were investigated. The optimum catalyst (SP25) was obtained through impregnation of γ-Al2O3 particles with an aqueous solution of ammonium tetrathiomolybdate (ATTM) and certain complexing agent, drying at 120℃ for 12h, then impregnation with an aqueous solution nickel nitrate and ammonium dihydrogen phosphate, drying at 120℃ for 12h, at last calcined at 500℃ in N2 atmosphere for 3h. The as-prepared catalyst SP25 exhibited a specific surface area of 212.3m2/g, pore diameter of 11.3nm, pore volume of 0.60mL/g, particle size of 17.3μm, skeleton density of 2.79g/cm3; the active components in the asprepared catalyst were in sulfided form and presulfurization was not necessary before using. XRD and H2TPR suggested that the addition of complexing agent during impregnation could enhance the dispersion of MoS2 on γAl2O3. Under the conditions of 350℃, 6MPa, wcatal/woil = 6%, reaction time 2h, the efficiencies of hydrodesulfurization and hydrodenitrogenation for FCC diesel oil reached 85.1% and 82.0%, respectively.