Abstract: The slot-type porous plug used for injecting pulverized coal into the ladle through a bottom position is an extremely important element for desulfurization during hot iron pretreatment, and it makes great effect on the trouble-free operation of this desulfurization technology. With the help of the Eulerian—Eulerian model and the particle dynamic theory, a three-dimensional model is constructed to evaluate the velocity, pressure and concentration fields of gas—solid two-phase flow in the slot of a porous plug. It is found that the concentration nonuniform length in the slot is about 250mm, the acceleration length is always less than 250mm, and the maximum difference in pressure is 2350 Pa on condition that the particle size is 20 μm. The result of industrial application shows that the desulfurization efficiency of coal injection through the bottom position is about 15% higher than that by the top lance.