A new method to prepare large amount of high purity single-walled carbon nanotubes is reported. In this method, a fixed-length metallic graphite anode is arranged at a given angle with the cathode, and then discharged for several minutes in high-temperature helium arc. By using this method, more than one-gram product containing about 60 percent single-walled carbon nanotubes can be obtained, which has been confirmed by the repetitive experiments and transmission electron microscopy (TEM) analysis.