Large amounts of single-wall carbon nanotubes(SWNTs) deposited on all the wall of the chamber have been obtained in helium and nitrogen mixed atmosphere using Co-Ni alloy catalyst with a modified arc furnace which can control the temperature during arcing process. Additionally, there are many weblike deposition products located between the cathode and anode. By twostep purification:the as-grown SWNT was heated in air at 500℃ for 30min, then soaked in 37% hydrochloric acid for 72h and filtered with deionized water. Microanalysis was carried out by Transmission electron microscopy(TEM), high-resolution TEM and Raman spectroscopy. The results obtained indicate that the purified SWNTs have high purity (higher than 95%) and uniform diameter (from 1.24 to 1.38nm).This experiment indicates that the temperature strongly affects the production of SWNT; the production and purity of SWNT increase with temperature. When the temperature is 600℃, the purity is about 70% and the production of SWNT is 12g/h.