The feasibility analysis of sintering flue gas desulfurization and denitration technology for ultra-low emission under high sulfur flue gas (high SO₂ concentration) condition is analyzed, and the technology for desulfurization and denitration of high sulfur sintering flue gas is screened to achieve ultra-low emissions: limestone-gypsum desulfurization + SCR denitration. Combining with the characteristics of high sulfur sintering flue gas, a suitable technical route is put forward: electrostatic precipitation + limestone-gypsum desulfurization + non-wet electric deep purification + primary flue gas supplementation + GGH + secondary flue gas supplementation + medium temperature SCR denitration. The ultra-low emission process based on this technical route is applied to the treatment of high-sulfur sintering flue gas, and the mass concentrations of particulate matter, SO₂ and NO_x in the treated flue gas are 7.01, 8.25 and 35.31 mg/Nm³, respectively, which could achieve ultra-low emissions continuously and stably.