Method for producing sweet gasoline

A process for preparing low-sulfur oil comprises, slicing the gasoline raw material into light and heavy distillate, contacting the heavy fraction and hydrogen gas with hydrodesulphurization catalyst for selective hydrogenation desulfurizing reaction, mixing the exudates separated by hydrogenation produced oil through high pressure separator with the light distillate, and contacting the hydrogen gas and hydrodesulphurization alcohol catalyst for hydrogenation desulfurizing reaction, separating the reaction exudates to obtain lighter hydrocarbons and gasoline products, and circulating the hydrogen-rich gas.