Abstract: Twisted nematic (TN) liquid crystal display mode cells doped with single-walled carbon nanotubes (SWNT) and multiwalled carbon nanotubes (MWNT) were prepared. The effects of SWNT and MWNT on the driving voltage, contrast ratio and response time of TN liquid crystal display mode cells were investigated with a liquid crystal display parameters tester. It was found that the addition of SWNT and MWNT remarkably decreased the driving voltage and decreased the contrast ratio significantly. The fieldon response time (t_on) and field-off response time (t_off) of TN liquid crystal display mode cells doped with SWNT were higher than those of pure TN liquid crystal display mode cells. For TN liquid crystal display mode cells doped with MWNT, t_off was reduced, but the variation of t_on had no obvious rules.