Abstract: The standard κ-ε model, VOF multiphase flow model and porous zone model were adopted to simulate residual slag in a blast furnace hearth under different deadman conditions. It is shown that the residual slag almost concentrates in deadman and the coke distribution in the peripheral region of deadman is the key factor influencing the total residual rate of slag. Deadman state below the lowest slag-iron level has little effect on the total residual rate of slag. Since the liquid iron and slag velocity near the taphole region is much greater than that in deadman, a downward-to-taphole gas-slag interface is formed. The taphole is stopped when gas begins to blow out, which causes much slag to have no time to drainage out. Improving the permeability of deadman is a very effective method to decrease the residual rate of slag.