The authors presented a conventional triode ionization gauge with a linear-type carbon nanotube cold electron emitter, which was made by painting technology on a nickel wire. The gauge used the ratio of the ion cur-rent to the electron current to indicate the vacuum. Although there was fluctuation in the cathode's emission current, the ratio of the ion current to the electron current kept stable with a variation of about +/-10% in-each pressure decade from 10(-7) to 10(-3) torr. The gauge showed good measurement linearity in the vacuum range from 10(-6) to 10(-3) torr. (C) 2008 American Vacuum Society.