In the hot metal pretreatment conditions, the direct current electric field is applied to study the new desulfurizer of magnesite to achieve the goal of in situ desulfurization instead of metal magnesium. A total of three desulfurizers were selected and the melting point, viscosity, primary crystal temperature, density and conductivity were measured and analyzed. The results can be shown that 18 %NaF-63 %MgF 2-12 %CaF 2-7 %MgO is the study of the latest desulfurization agent.