Semi-solid powder processing (SPP) is a promising technique in the fabrication of composite materials. Former work has experimentally shown that SPP was able to synthesize composite materials with reduced load and high efficiency. However, limited work was found in the modeling of the SPP. In this work, SPP was modeled with Shima-Oyane’s model and compared with experimental data in a closed die compaction setup. The evolution and distribution of the density and stress were analyzed. The model prediction agreed with the experimentally measured values. As the compaction pressure increased, the density gradient in the axial compaction direction decreased, while the stress gradient increased.