Abstract: The Ni-Mo-W catalyst precursors were prepared by co-precipitation method and then the Ni-Mo-W catalysts were finally obtained by drying, molding, and calcination. The synthesized catalysts were mainly investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XRS), scanning electron microscopy (SEM). The coprecipitation mechanism of nickel nitrate solution, ammonium molybdate, and ammonium tungstate solution was studied. The results show that after the pHs of material Ni(NO3)2?6H2O，(NH4)10W12O41?xH2O，(NH4)6Mo7O?4H2O was adjusted by ammonia water, coprecipitation under appropriate conditions was conducted. The composition of the precipitate is mainly composed of (NH4)Ni2Mo2O8(OH)?H2O and Ni4W6O21(OH)2?4H2O. NiWO4 and NiMoO4 were obtained after calcination of the precipitate. Ni-Mo-W compounds have layered structure. It is found that nickel ion first combines with tungsten acid radical ion, forming layered compound board, and then the molybdate come into the layer, resulting in Ni - Mo - W bulk catalyst precursor.