Herein we report a CVD approach to prepare high-density and perfectly aligned arrays of along SWNTs on stable temperature (ST)-cut quartz substrates using copper as catalyst and ethanol as carbon sources. Compared with earlier reports, we have demonstrated that the aligned nanotube arrays can be grown on ST quartz substrate without the need of thermal annealing. The density can reach >50 nanotubes per micron and the length can be a few millimeters. Additionally, we have obtained direct proof on the "tip-growth" mechanism for the aligned nanotubes and important evidence that explained the termination of the growth.