A deep eutectic solvent was synthesized by the stirring method with Br?nsted acid (carboxylic acid) and Lews acid (ferric chloride) as raw materials. It was then analyzed with a Fourier transform infrared (FTIR) spectrometer. The results showed that the deep eutectic solvent was formed by hydrogen bonding between Br?nsted acid and Lews acid. Extraction desulfurization with this deep eutectic solvent as the extractant was investigated, and the optimum desulfurization conditions were obtained as follows. When the molar ratio of Br?nsted acid to Lews acid is 1 : 0.5, the desulfurization temperature is 30 °C, and the ratio of solvent to oil is 1 : 5, the proposed extractant demonstrates a favorable desulfurization effect on the simulated oil, gasoline, and diesel.