Powder-binder separation based on the governing equation combining the shear-induced particle migration and non-Newtonian viscosity models suggested by Phillips and Krieger, respectively in the powder injection molding is numerically and experimentally investigated. An essential condition for steady-state of the Phillips model to be valid was mathematically derived. The effects of rheological and processing parameters including n, ϕm, and ϕ0 were numerically analyzed. For the experimental analysis, three different particle sizes of SUS17-4PH powder and wax based organic binder system were employed. The critical solid loading and rheological parameters for non-Newtonian viscosity model based on power law and Krieger models were obtained by data treatment obtained from torque and capillary rheometry experiments, respectively. The extracted feedstock through the capillary die was polished to measure the powder distribution in specially designed zig. The powder volume fraction on the surface of microstructure was measured and then calculated by image analysis. The ratio of diffusive coefficients, in the conservation equation proposed by Phillps et al. were determined by mean residual method. In order to analyze the influence of each term for governing equation, parameter study in terms of shear rate, viscosity, and diffusion was performed.