Surface dielectric barrier discharge plasma is promising in improvement of the aircraft aerodynamic characteristics and propulsion efficiency. This paper reports characteristics of the surface dielectric barrier discharge plasma at pressures varying from 2 to 760 Torr. As the pressure decreases, the discharge mode changes from a filamentary type to a glow type at around 45 Torr. The N2(C3IIu) rotational temperature decreases, while its vibrational temperature increases. In the filamentary mode, the intensity ratio of 391.4 nm and 380.5 nm, as a rough indicator of the average electron energy, remains almost unchanged. While in the glow mode, the intensity ratio of 391.4 nm and 380.5 nm increases abruptly while the pressure decreases.