Abstract: Quartz crystal was synthesized from silicon tetrachloride of polysilicon by-product by hydrothermal method with anhydrous sodium carbonate as mineralizer at different reaction temperatures.XRD，SEM，and EDS were used to characterize the structure，morphology，and chemical components of the as-prepared quartz crystals.Results showed that the crystal phase of the as-prepared quartz was typical low-temperature α-SiO₂，which was prismatic and grew in the direction of axial；the size of quartz crystal increased gradually with the increasing of reaction temperature，appeared to have the maximum size at  220 ℃，and average particle size was about 8 μm；but when reaction temperature reached 230 ℃，the size of α-SiO₂ crystal became smaller.

Key words: quartz crystal, silicon tetrachloride, hydrothermal method, high-purity