The high-energy ball milling method was adopted to explore the influence of ball milling parameters, such as milling speed and additive amounts of process control agent (PCA) on tungsten powder. The morphology and microstructure of tungsten powder in the process of refinement were characterized by field-emission scanning electron microscope (FE-SEM), field-emission transmission electron microscope (FE-TEM), and X-ray diffractometer (XRD). Results revealed that the ball milling process and the refinement of tungsten particle and grain can be largely influenced by these two parameters. The milling efficiency was found to be highest with the milling speed of 700 rpm and additive amounts of 8% PCA. The mechanisms for the effect of these two parameters and milling time on the refinement process were discussed. Nanocrystalline tungsten powder with a particle size and grain size smaller than 100 nm was obtained, and the grain size of 5–15 nm was fabricated successfully under the highest milling efficiency conditions.