Abstract: This study systematically investigated the sintering microstructures and densification behaviors of spherical versus irregular tungsten powders via a combined hot pressing (HP) and hot isostatic pressing (HIP) approach. During the HIP stage, irregular FW9 powder achieved densification through coupled grain boundary diffusion and plastic flow, whereas spherical SW15 and SW25 powders exhibited progressively reduced densification efficiency dominated by plastic flow and surface diffusion mechanisms, respectively. Notably, the broad particle size distribution of SW25 critically constrained its densification process. Microstructural characteriza-tion revealed distinct differences: FW9 sintered compacts displayed an average dislocation density of 0.577 ×1014 m-2, 24.4% low-angle grain boundaries (LAGBs), and a wide grain size distribution (25–250 μm) with an average of 76.04 μm and pronounced crystallographic texture. In contrast, SW15 and SW25 showed higher average dislocation densities (0.8 ×1014 m-2 and 1.3 ×1014 m-2, respectively), elevated LAGB fractions (62.4% and 75%), and uniform grain sizes (44.68 μm and 50.15 μm) without preferential orientation, indicating in-tensified lattice distortion and plastic deformation in spherical powders during sintering. These results demonstrate that spherical powders significantly enhance grain size uniformity and suppress abnormal grain growth while avoiding texture formation. This work provides critical insights for tailoring high-performance tungsten sputtering targets through powder morphology optimization.