Polyaniline/carbon nanofiber (PANI/CNF) composite materials were prepared by in situ polymerization. The functional group, composition, surface morphology, and specific surface area of composite materials were characterized by Fourier transform infrared (FT?IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and Brunauer?Emmelt?Teller analysis. Cyclic voltammetry (CV) and galvanotactic charge?discharge methods were used to study the electrochemical properties of the PANI/ CNF composite materials. Results showed that the composite materials had a rough surface with a burry PANI structure that was uniformly distributed over the CNF. The composite materials, as electrodes, showed good reversibility in redox reactions. The specific capacitance of 44.4%(w) PANI/CNF was 587.1 F·g-1, the specific energy was 66.1 Wh·kg-1 at a current density of 100 mA·g-1, and the specific power was 1014.2 W·kg-1 at a current density of 800 mA·g-1. Moreover, the specific capacitance of PANI/CNF only decreased by 28% after 1000 charge?discharge cycles. Therefore, the PANI/CNF composite material is an excellent material for use in supercapacitors because of its high electrical conductivity and large specific capacitance.