The invention relates to a preparation method of a 
quartz product, and especially relates to a preparation method of a low-hydroxyl large-
diameter large-length 
quartz piece. According to the invention, the piece is prepared with a 
plasma vertical 
solid-phase external deposition method. One or a plurality of 
plasma torches can be configured. During a 
smelting process, the 
plasma torch is maintained unmoved, or is subjected to translational motions up and down on a 
vertical axis. The 
smelting temperature which is 
quartz piece surface temperature is 1800-2500 DEG C. 
Quartz sand is delivered in from a blanking 
pipe at a 
plasma torch upper port or by plasma device central 
airflow. A central base 
pipe or base rod is fixed on a glass 
machine tool, and simultaneously rotates when performing translational movements up or down on the 
vertical axis. Along with the relative movements of the 
plasma flame and the central base 
pipe or base rod, the quartz sand is deposed and molten layer by layer, such that a hollow quartz blank piece or a 
solid quartz blank piece is formed. With the plasma vertical 
solid-phase external deposition novel method, the prepared quartz piece has the characteristics high purity, low hydroxyl content, high 
softening point, high strength, high 
temperature resistance, and uniform 
diameter.