Abstract: Based on the chemical conversion properties of the constituents of phenolic-based C/C composites during liquid-phase impregnation process and Arrhenius equation, the manufacturing process mechanical model for C/C composites was established. The variations of volume fraction of different component phases in two important stages of solidification-carbonization and graphitization were analyzed. The volume fraction of pores obtained by simulations is in a good agreement with the experimental results obtained by image processing of Micro-CT system for the actual fine-woven punctured C/C composites. Combined with homogenization method, the effective elastic modulus of matrix during manufacturing process was predicted. The results show that the effective elastic modulus of matrix increases with the increasing of the densification times. The elastic modulus of matrix in each densification process increases first and then decreases. After solidification process, the elastic modulus of matrix approaches a stable value.