Aligned CNx nanotubes were fabricated by pyrolyzing ethylenediamine on p-type Si(111) substrates deposited by Fe catalysts. Scanning electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy were used to characterize the CNx nanotubes. The CNx nanotubes about 20μm in length and 50-100?nm in diameter have the “bamboo-like” structure and worse crystallinity. Field emission measurements of the CNx nanotubes indicated that 20μA/cm2 current densities were observed at an electric field of 1.4V/μm，and 1.280mA/cm2 were obtained at 2.54V/μm. No current saturation was found under higher electric field. The CNx nanotubes exhibit better field emission properties than carbon nanotubes and BCN nanotubes that have been grown under same experiment conditions only using different precursor solution. The emission mechanism of CNx nanotubes is also discussed based on their “bamboo-like” structures.