Abstract: Low-cost,high-quality single-walled carbon nanotubes（SWNTs） have been firstly synthesized by DC arc discharge using low-pressure air as buffer gas and Fe-S as the catalyst.Numerous experiments show that the best growth condition of SWNTs is the steady air pressure from 6 to 12 KPa via controlling the input and output of air flow.The as-synthesized SWNTs were characterized by scanning electron microscopy（SEM） and transmission electron microscopy（TEM）.Results suggest that as-synthesized SWNTs have high crystalline and low impurities,and the diameter distribution ranges from 1.5 to 6.0 nm.This approach opens up new possibilities for low-cost synthesis of high-quality SWNTs.