The invention discloses a preparation method of a catalyst for hydrotreating of a fluidized bed. The preparation method includes the following steps: (1) kneading and forming pseudo-boehmite and alkaline ammonium aluminum carbonate of a adsorption carbon precursor solution, and drying a formed product; (2) spraying the material obtained in step (1) by a solution containing carbon precursors, and drying and roasting the soaked material to obtain an alumina carrier; (3) impregnating the alumina carrier obtained in step (2) by impregnation liquid containing hydrogenation active components, and drying and roasting the alumina carrier after impregnation to obtain the catalyst for hydrotreating of the fluidized bed. The catalyst prepared by the method has higher strength and wear resistance, andis particularly applicable to the hydrotreating process of heavy-oil fluidized beds.