Abstract: Polyacrylonitrile-based hollow, porous carbon fibers (PAN-HPCFs) as lightweight radar wave absorbers were prepared by the oxidation of PAN hollow fibers in air followed by carbonization in nitrogen. The effects of oxidation time and carbonization temperature on the microstructure, composition, electrical conductivity and complex permittivity of the resulting PAN-HPCFs were investigated. Results indicated that heat-treatment parameters had no obvious effect on the microstructure of the PAN-HPCFs. The carbon content of the PAN-HPCF decreased, the nitrogen content increased and the electrical conductivity decreased with oxidation time. The real and imaginary parts of the complex permittivity (ε' and ε″) decreased with oxidation time. The electrical conductivity and complex permittivity of the PAN-HPCFs can be adjusted by changing the heat-treatment parameters. The values of ε' and ε″ of PAN-PHCFs were 17.20 and 11.90 respectively and the electrical conductivity was 564.50Ω^-1 · m^-1 when oxidation time was 60 min and carbonization temperature was 800℃.