Abstract: Phenolic fibers were prepared by melt-spinning a novolac resin and then crosslinking. Weight loss, FT-IR, X-ray analysis, SEM measurments, microporosity, electrical conductivity and tensile strength measurements were used to study the microstructure of phenolic fiber pyrolyzed at different temperatures. It is found that the BET surface areas exhibit a maximum value of 1040m2/g at 850℃ with heat treatment temperature (HTT) and micropores resulted from the paths left by volatiles formed at HTT between 450～900℃.