Abstract: Spherical pure tungsten powders for laser powder bed fusion （LPBF） were surface-activated by hydrofluoric acid etching （acid-based activation） and hydrogen peroxide etching （alkali-based activation）, separately. The effects of the two processes on surface morphology and properties of tungsten powder were studied. The results show that the powder particles retained their spherical shape after acid activation, with localized nanoscale protrusions appearing on the surface, and no obvious impurities were introduced. The alkali-activated powder particles were transformed into a cuboid-like structure, covered with uniform, dense, and finer nanoscale protrusions, and a small amount of tungsten oxides was detected on the surface. After acid and alkali activation, the flow time for 50 g of tungsten powder through a 2.5 mm aperture increased to 18.47, 5.82 s, respectively, indicating a decrease in flowability comparing to the unactivated powder. The laser absorptivity （at wavelength of 1 070 nm） of the acid activation tungsten powder and the alkali activation tungsten powder was 69.60%, 72.15%, and the relative density of the sintered samples with the two powders above was increased to 95.97% and 96.24%, respectively. The laser absorptivity and the sintering densfication after activation increased comparing to the unactivated powder, and the alkali-based activation process yielded superior improvement.