Abstract: The fracture surfaces of high-performance pitch-based carbon fibers after monofilament tensile testing were observed by scanning electron microscopy, and the relation between tensile fracture and tensile strength was analysed. The results show that pitch-based carbon fibers had characteristic fracture morphology of clear graphite crystallitic structure. The tensile fracture of low-strength carbon fibers was relatively smooth, the fracture surfaces became rough and uneven with the increase of the tensile strength, and graphite crystallitic fragments were observed in certain zone of tensile fracture surface of high-strength carbon fibers.