The bamboo-shaped nitrogen-doped carbon nanotubes (CNx) with different nitrogen content were synthesized using Fe-containing SBA-15 molecular sieve as catalyst with thermal decomposition. The CNx nanotubes prepared were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and Raman spectroscopy. The results suggest that there are a larger amount of defective sites on CNx nanotubes surfaces due to the nitrogen doping and CNx nanotube with higher nitrogen content possesses lower graphitic ordering in the framework. Furthermore the effects of nitrogen content on the electrochemistry of CNx modified electrodes were investigated by cyclic voltammetry (CV). CNx modified electrodes exhibit better electrocatalytic activities to the oxidation of hydroquinone. Moreover CNx with lower nitrogen content is in favor of the electron transfer between dihydroxybenzene and electrode surface, while CNx with higher nitrogen content possesses high surface adsorptive ability. CNx modified electrodes can be applied to determine dihydroxybenzene isomers directly and simultaneously by linear sweep voltammetry technique without previous separation.