Deep eutectic solvents (DESs) have important application prospects in fuel desulfurization. A novel dual Brønsted acidic DES was proposed and successfully synthesized for one-pot oxidation-extraction desulfurization process, in which a green and harmless choline chloride (ChCl) was used as hydrogen bond acceptor, p-toluenesulfonic acid (TsOH) and oxalic acid (OA) were used as hydrogen bond donors to provide acidic groups. The results showed that the new DESs (ChCl/2TsOH/0.2OA) had the excellent desulfurization efficiency due to the strong acidity based on the synergistic effect between the two acidic groups. The content of benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) could be reduced to 8.82 ppm (120 min), 1.23 ppm (90 min), and 7.75 ppm (90 min), respectively. Electron spin resonance and radical capture experiments showed that superoxide radicals (·O2–) were the main oxidizing agents. The possible oxidation-extraction pathway was that DBT was extracted from oil phase into DES phase, and the DES was converted to peroxy acid in the presence of ·O2–, then the extracted DBT in DES phase was oxidized to high polar sulfone. It can be regenerated and recycled by simple water washing. To improve dispersion and treatment efficiency, reduce the amount of DESs, the viscosity of DESs was adjusted by using sulfolane as the dilute, which could significantly reduce the operation time and enhance the desulfurization effect. The content of BT, DBT, and 4,6-DMDBT could be reduced to 12.20, 2.21, 7.38 ppm only need 45, 5, and 15 min, correspondingly. The novel green DES can provide theoretical support and technical guidance for deep fuel desulfurization.