Preparation method for alumina dry gel

The invention discloses a preparation method for alumina dry gel. The method comprises the following steps: in the process of gel formation by concurrent flow of an alkaline solution containing aluminum and an acidic solution containing aluminum, adding an additive and an organic template agent in the manner of concurrent flow at the same time, controlling proper reaction conditions and carrying out gel formation, wherein the organic template agent is cellulose ethers; then adding an alkaline solution to adjust a pH value; and then carrying out filtering, washing and drying so as to obtain the alumina dry gel. The alumina dry gel prepared by using the method has the advantages of a large specific surface area, a great pore volume and a reasonable pore structure and is particularly applicable as a carrier component for a heavy oil hydrotreating catalyst, especially applicable as a carrier component for a residual oil hydrodesulfurization or hydro-conversion catalyst.