Abstract: The substrate architecture of carbon/carbon composites has an effect on both properties and cost of products. In this paper, four kinds of substrate architectures, that is, 1K carbon cloth, 3K carbon cloth, 1K carbon cloth+carbon paper, 1K carbon cloth+carbon felt, were selected. The compositing technology was by the improved CVD methods. The influence of substrate architectures on the properties and microstructure of the manufactured carbon/carbon composite was studied. The results show that the samples made by the four kinds of architectures all have an obvious pseudoplastic fracture behaviour and the macroscopic appearance of bending fracture fractography shows as a “Z” shape. The sample manufactured by 1K carbon cloth has the highest flexural strength, and that by 3K carbon cloth has a lowest value. The strength of other two kinds of samples is between the two.