Thermal debinding in metal powder injection molding (MIM) is an intricate phenomenon and time-consuming procedure. A two-dimensional debinding model, based on Darcy's law, is developed to simulate the movement of the binder flow front and to predict the debinding rate. In the present model the wick powders are put around the compact. For simplification, the assumption of a single component binder is adopted. The body-fitted finite element method is used in the numerical simulation. Results show that the debinding rate is faster in the present model than that in Vetter's model for the small MIM parts. The total debinding time can be reduced as the contact surface area of the compact-wick combination increases. The binder removal is fast as the debinding process is performed at high temperature. By similarity analysis, we also show that the debinding rate and flow field are similar at various temperatures for the same compact-wick combination.