By using Y-Ni-C composite rod as cathode, large amount of single-walled carbon nanotubes was produced by an improved arc discharge method, in which a tungsten rod was used as an electrode and the electrodes were exchanged after each discharge. The raw soot was characterized by high resdution electron microscope and Raman spectrum, and the results show that this is an efficient way to produce large amount of single-walled carbon nanotubes.