Abstract: On the basis of experimental data, a densification rate mode to describe the woven preform deposited in the thermal gradient CVI process was put forward. It was found to be fit to the index densification equation which was usually used to describe the kinetic process that organic molecules filled in pores of substrate as well as in the ICVI process. Simultaneously, it was also found that the thermal gradient field and the directional flow field of input gas within the deposited preform could largely raise the densification rate of the preform, for they can accelerate the diffusion rate of filled molecules and reduce the surface crust formation of the preform in the thermal gradient CVI process.