Carbon nitride nanotubes (CN-NT) thin films were prepared on Ni-Cr coated glass substrate by microwave plasma enhanced chemical vapor deposition at a relatively low temperature of 600 similar to 650 degrees C. The morphology of the films were observed by scanning electron microscopy. The microstructure of the film were analyzed by x-ray photoelectron spectroscopy, x-ray diffraction, and Raman spectroscopy. The characteristics of field emission of CN-NT thin films were measured. Experimental results indicate that the film structure and properties of the field electron emission are related to flow ratio of N-2 to CH4. When the flow ratio of N-2 to CH4 was 3.3, the obtained film had a better field electron emission characteristics. The turn-on field of the film was 3.7 V/mu m. The current density was 413.3 mu A/cm(2) at an electric field of 8 V/mu m.