The invention belongs to the fields of material chemistry, gas separation or purification and the like, and relates to a novel preparation method for an efficient desulfurization agent, wherein an ultrasonic synergism method is adopted to prepare the supported desulfurization agent. The preparation method comprises: dissolving tetraethoxysilane in an alcohol mixed solution, and carrying out stirring heating, wherein a mass ratio of the tetraethoxysilane to the alcohol mixed solution is 0.1-1:1, and the heating temperature is 50-100 DEG C; and adding Na2CO3 to the obtained solution, continuously carrying out mechanical stirring, opening an ultrasonic irradiation device, and adding distilled water to produce a transparent gluey material, wherein the reaction temperature is 50-100 DEG C, and the reaction time is controlled to 1-10 h; and closing the ultrasound, and aging the gluey material at a room temperature to obtain the target desulfurization agent. With the preparation method for ultrasonic preparation of the supported desulfurization agent, the excellent desulfurization agent with characteristics of high specific surface area, high activity, good desulfurization performance and more recycling times can be prepared, and requirements of researches and applications of the after-combustion dry desulfurization can be easily met.