N-doped carbon nanotubes with different nitrogen contents were synthesized by CVD with pyridine as nitrogen source and acetylene as carbon source. The samples’ morphology and bonding properties were characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). TEM images showed that with the increasing nitrogen content, the average bamboo segment distance of the carbon nonotubes decreased from 120 nm to 40 nm and more flexural tubes with coarse surface was obtained. XPS results revealed that there are pyridinic, pyrrolic and graphitic types of C-N bonds in the N-doped carbon nanotubes. The effect of nitrogen content on the bonding property was analyzed. And the chenge in morphology with increasing nitrogen content was explained by the difference in bonding forms.