Abstract: A serial of contrast experiments were carried out on induction furnace. It's found that a betterdesulphurization result exists in the top slag plus sire injection Process than in the single top slag process. Slag which contains BaO has stronger desulphurization ability than that does not. CaSi alloy can decrease the terminal sulphur content in the steel whenO andS are low Further, some basic technological parameters were proposed for the refining of ultra-low sulphur steel.