Based on the dielectric property of carbon nanotube film, the surface plasmon ploariton propagation and localization phenomena on the carbon nanotube film are investigated using THz time-domain spectroscopy technique. The simulation results show that in the gate period of 168um, the resonance peaks of surface plasmon mode are at 0.99THz and 1.95 THz, which are consistent with the theoretical results. Further analysis demonstrates that both the gate thickness and the width have an important effect on the properties of surface plasmon ploaritons.