A single-layer double-walled carbon nanotube (DWNT) membrane, with 100 cm2 in area, 50 nm in thickness, was spread by adding a few drops of ethanol (or acetone) on the purified DWNTs. Compared with acetone, ethanol is more efficient in spreading DWNT films. The spreading rate of DWNT membrane increases with the ethanol concentration, and it also first increases with temperature (below 60℃), then decreases as the temperature rises to above 60℃.