A pixel tube for a field-emission illumination/display device includes a sealed container, an anode electrode, a cathode electrode and a shielding electrode. The sealed container has a light permeable portion. The anode electrode is disposed in the sealed container and adjacent to the light permeable portion. The cathode electrode is arranged in the sealed container facing the anode electrode and includes a cathode supporter and a carbon nanotube yarn, the carbon nanotube yarn attached to the cathode supporter and extending toward the anode electrode for emitting electrons therefrom. The shielding electrode is disposed on a surface of the sealed container and surrounds/encircles the carbon nanotube yarn.