The invention provides a preparation method of sulfur-free gasoline. The preparation method of sulfur-free gasoline comprises the following steps: (1), contacting poor-quality gasoline raw materials with selective hydrogenation catalyst in a selective hydrogenation reactor in the presence of hydrogen so as to carry out selective hydrogenation reaction; (2), contacting the product of the step (1) with a first selective hydrogenation and desulfurization catalyst in a first selective hydrogenation and desulfurization reactor so as to carry out the first selective hydrogenation and desulfurization reaction; (3), sending the product of the step (2) into a H2S stripping column, so that an air phase containing H2S is obtained at the top of the column and a liquid phase with H2S removed is obtained at the bottom of the column; (4), contacting the liquid phase obtained in the step (3) with a second selective hydrogenation and desulfurization catalyst in a second selective hydrogenation and desulfurization reactor; and (5), contacting the product obtained in the step (4) with a hydrogenation refining catalyst in a hydrogenation refining reactor. The method disclosed by the invention is capable of preparing sulfur-free gasoline whose sulfur content is no higher than 5 micrograms/gram; moreover, the sulfur-free gasoline is relatively small in octane value loss. In addition, the preparation method is high in product yield.