The invention provides a preparation method of a silicon-containing macroporous alumina carrier and a hydrotreating catalyst. The preparation method of the carrier comprises the steps of (1) dipping pseudo-boehmite dry glue powder into a water solution containing polyhydric alcohols and/or carbohydrates and then carrying out hydrothermal carbonization treatment on the dipped material; and (2) dipping carbon black powder into a silicon-containing solution, mixing and kneading the carbon black powder with pseudo-boehmite obtained in the step (1), an extrusion aid and a peptizing agent into a plastic body, carrying out extruding and drying, roasting the dried material under a nitrogen atmosphere and then roasting in an air atmosphere to prepare an alumina carrier containing silicon dioxide. The hydrotreating catalyst comprises the carrier and a hydrogenation active component. The alumina carrier prepared through the method has relatively high mechanical strength while having relatively large pore volume and pore diameter, and is suitable for the field of preparation of heavy oil or residual oil hydrodemetallization catalysts.