The electrocatalytic oxidation of nitric oxide(NO) at a glass carbon electrode(GC) modified with functionalized single-walled carbon nanotubes(SWCNTs) was investigated by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS). It was found that the SWCNT modified electrode could speed greatly up the electron transfer rate compared with the bare GC electrode. After the SWCNT was treated with alkali or mixed acids, the reaction rate and activation energy of NO electrooxidation were changed to different extent. Chemical modification of the SWCNT surface is one of the most powerful methods to change the sensitivity of NO electrooxidation reaction. The modified electrode with SWCNT obtained by the firstly alkali treatment and then the mixed acids treatment was the best one for NO electrooxidation, the result of CV was also confirmed by that of EIS. The anodic processes of NO were recognized more clearly by exploring the reaction mechanism of NO electrooxidation at the SWCNT modified electrode.