A technology for producing ultralow-sulfur steel with steel ladle as refining furnace features that the efficient non-metal desulfurizing powder is used to make cored wire, and the cored wire is fed into molten steel while inertial gas is brown into it from the bottom of steel ladle to stir the molten steel for speeding up the desulfurizing reaction. Said desulfurizing powder contains BaO (5-40 mass%), CaO (50-80) and CaF2 (8-15). After refining the steel for 15-35 min, the sulfur content is reduced from 0.01% to 0.001%.