Drainage behavior in the hearth plays an important role in the operation of ironmaking blast furnaces, as the undisturbed extraction of the produced liquid iron and slag is a prerequisite of smooth operation. An improved two-fluid model for simulating the drainage behavior of iron and slag in a blast furnace hearth is developed in this work. A piecewise-linear interface calculation scheme for interface tracking is utilized to prevent interfacial penetration, and a general expression of the drag force for stratified flow is applied between the liquid phases. A theoretical equation between the drainage rate and the interface tilt angle near the taphole is also proposed. The actual iron-slag system and a water-oil system, which is often used in small-scale physical models of a furnace hearth, were simulated by the two-fluid model and by the well-established volume of fluid model. The differences between the results of the two numerical models were studied for a short-term drainage process, and the performance of the models was analyzed with respect to their predictions of the interface between the liquids and the angles of the interface dose to the taphole.