The work aims to prepare helical carbon nanofibers by the ethanol flame method, and examine the effect of different surface modification methods on the hydrophilicity of the as-synthesized helical carbon nanofibers. Firstly, the effects of different burning time, nickel-flame distances and SnCl4 solution concentrations on preparation of helical carbon nanofibers were studied; and then the helical carbon nanofibers were modified with water vapor, polyvinylpyrrolidone K30 (PVP) solution and sodium hydroxide-concentrated nitric acid solution (KOH-HNO3), respectively. The prepared helical carbon nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and X-ray diffraction (XRD), and the influences of different modifications were evaluated by infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and sedimentation experiments. The experimental results showed that increasing the nickel-flame distance could extend the yield of spiral carbon nanofibers, but deteriorate the uniformity gradually, while burning time lead to fluctuation of the uniformity. In addition, the concentration of SnCl4 could also affect the morphology and uniformity of the carbon nanofibers. The optimal parameter for preparing uniform helical carbon nanofibers was: 73% SnCl4 solution, 1.5 cm of nickel flakes-flame distance and burning for 9 min. The FTIR revealed that hydrophilic groups can be grafted on the surface of the helical carbon nanofibers by all the three modification methods. The sedimentation experiments showed that the PVP solution or KOH-HNO3 modified helical carbon nanofibers possessed better hydrophilicity than water vapor modification, and after standing for 48 h, their sedimentation rate in aqueous solution decreased from 58.3% to 26.7% compared with unmodified helical carbon nanofibers. In conclusion, ethanol flame method can be used to prepare uniform helical carbon nanofibers whose morphology and uniformity can be controlled by burning time, nickel-flame distance and SnCl4 solution concentration. Uniform helical carbon nanofibers could be prepared under special conditions. It is found in modification through the three methods that PVP solution or KOH-HNO3 modified nanofibers show better hydrophilicity than ones modified using water vapor. The modification of PVP solution is easy to be operated and does not damage the morphology of helical carbon nanofibers. It is more beneficial to the modification of spiral carbon nanofibers.