Abstract: The large-scale synthesis of vertically-aligned carbon nanotube arrays with different helical pitches and diameters was achieved using the floating catalyst method. Results indicate that they are aligned perpendicular to the substrate surface and have a well-graphitized structure and their growth is accompanied by the production of pentagonal, heptagonal and hexagonal carbon rings. The hexagonal carbon ring is the basic structure unit to form the graphite lattice. When paired pentagon-heptagon atomic rings arrange themselves periodically within the hexagonal carbon network, helical carbon nanotubes are formed. The growth rate of the helical carbon nanotubes is about 4.5mg/cm²·h.