Carbon‐like nanofiber (CNF) is synthesized using microwave plasma‐enhanced chemical vapor deposition. We present the effects of fluorocarbon and oxygen (CF4/O2) plasma‐treated on the microstructural, crystal, and field emission (FE) characteristics of CNF by SEM, transmission electron microscopy, micro‐Raman, and FE system. Results showed that the presence of the damaged CNF occurs at 2 min CF4/O2 plasma treatment and some amorphous carbon particles after 10 min CF4/O2 plasma treatment. One can also observe that turn‐on fields were enhanced (2.75 uA/cm2) at 2 min CF4/O2 plasma treatment; this indicates a remarkable FE enhancement of the local emission region in CNFs. Complementary information was obtained by thermal desorption atmospheric pressure ionization mass spectrometry and XPS. It can be found that the broken surface morphologies could be attributed to the chemical reaction exchanged via plasma excitation; a large number of bonding (C–F and C–O) in the CNF was detected. In addition, it is observed that the CNF has higher fluorine desorbed at 277.5 and 427 °C after CF4/O2 plasma treatment. Copyright © 2012 John Wiley & Sons, Ltd.