Two types of silicon carbide fibers (SiCf) were prepared employing different pyrolysis techniques. The relationship between the microstructure and the electrical resistivity of the fibers was investigated. The results indicated that the carbon layer present on the fiber surface acted as the main conductive phase in the SiCf obtained by direct pyrolysis, whereas a free carbon phase determined the conductivity of the SiCf prepared by the preheated pyrolysis method. A core-shell model and a general effective media (GEM) theory were proposed to explain the conductivity of different types of SiCf. Quantitative analysis based on these models indicated an electrical resistivity of similar to 10(-2) cm for the carbon layer on the surface of SiCf obtained by direct pyrolysis. The electrical resistivity and the percolation threshold of the free carbon in SiCf prepared by the preheated pyrolysis method were 10(-1) cm and 11.3% respectively.