Granular modeling of steel powder flow and compaction is proposed and developed to consider mechanical interactions between powders and binders for MIM, to predict change of viscosity and flow patterns in MIM and to make materials design and evaluations on MIM. Two dimensional channel flow problems are taken for numerical examples to demonstrate the validity and effectiveness of our approach. The effect of grain size distribution and injection threading speed on the powder flow pattern can be directly evaluated through the present granular model simulations.