Transparent SiO 2 bodies were prepared by pressureless sintering (PLS) and spark plasma sintering (SPS). The effects of sintering and annealing temperature on the transmittance of the SiO 2 bodies were investigated. The SiO 2 bodies sintered by SPS and PLS at 1073–1573K were amorphous. With increasing the sintering temperature to 1673K, the SiO 2 bodies sintered by PLS were crystallized while those sintered by SPS were still amorphous. The relative density of the SiO 2 bodies sintered by SPS was 98.5% at 1373K and 100% at 1573K, whereas that sintered by PLS was 92.6% at 1373K and 98.9% at 1573K. The transmittance was 91.0% and 81.5% at a wavelength (λ) of 2μm for the SiO 2 sintered bodies by SPS and PLS, respectively. In the ultraviolet range, the transmittance of the SiO 2 bodies sintered by SPS at 1573K was about 40% at λ=200nm and increased to 75% after annealing at 1073K for 1h, which was about three times of the transmittance of the SiO 2 bodies sintered by PLS (24.8%).