Abstract: Using the PFC three-dimensional numerical simulation software, the law of relative density change and force chain distribution during the pressing process were obtained by changing the particle size distribution of powders to establish the cold pressing models. Under the specific particle size ratio of powders, the compacts with the highest relative density could be obtained. In the results, the large, medium, and fine particles in the mass ratio of 60:15:25 show the highest compact relative density, and the compact relative density does not increase with the increase of the fine powder ratio. As the proportion of the additional fine powders rises during the pressing process, the greater strain can be generated in the pressing direction. The lateral pressure coefficient and Poisson's ratio are less affected by the particle size distribution of powders, which can decline due to the lack of sufficient driving force and displacement space in the case that the compacts have obtained the higher relative density in the later stage of the compaction. The number of force chains for the powders with the mixed particle size is much greater than that of the powders in the single particle size. In the case that the number of strong force chains is sufficient, the higher compact relative density can be obtained, combining a large number of weak force chains.