Abstract: The electric transport properties of an individual vertical multi－wall carbon nanotube (MWCNT) were studied in situ at room temperature in a scanning electron microscope chamber. It was found that the single MWCNT has a large current－carrying capacity, and the maximum current can reach 7.27 mA. At the same time, a very low resistance of about 34.4Ω and a high conductance of about 460—490G0 were obtained. This indicates that large diameter MWCNTs exhibit multi－channel quasi－ballistic conduction , which can be attributed to the participation of multiple walls in electrical transport and the large diameter of the nanotubes.