The deformation mechanism related to the initial relative density and uniformity of Cu-W composite powders under quasi-static compression was investigated by multi-particle finite element method. The results show that under the same pressure, the relative density of powder increases with the increase of initial relative density or the uniformity of composite powders. The densification processes can be divided into three stages, namely particle rearrangement, Cu particle deformation and W particle deformation. Pores are mainly filled by the rearrangement of particles and the deformation of Cu particles. The rearrangement and deformation of particles are quantitatively characterized by introducing the mean rotation degree and the mean equivalent strain of powders. It is found that smaller voids formed in the initial denser powder are easily filled by the deformation of ad jacent particles during compaction. Strong force chains formed by the contact of W particles severely hinder the compression, resulting in large porosity. (C) 2021 Elsevier B.V. All rights reserved.