Abstract: The polyacrylonitrile carbon felt was heated for 2 hours at 450-650 ℃ in air, respectively. The effect of heat-treatment temperature on surface state, structure and conductivity of the carbon felt were studied by scanning electron microscopy(SEM), Raman spectroscopy and resistance meter. The results show that the impurities gradually disappeared and some defects, such as holes and grooves, appeared with the increase of the heat treatment temperature. The structure of carbon fiber gradually changed from planar turbostratic structure to three dimensional ordered structure. The conductivity of carbon felt raised and then decreased, and reached the maximum at 550 ℃.