Abstract: According to the physicochemical properties of C/C composites and TaC and the environment, in which C/TaC/C composites is ablated, the ablation mechanism of C/TaC/C composites is deduced. It is analyzed in detail for C/TaC/C composites how to resist erosion and denudation. Then, its ablative model is established on the basis of analyzing the ablation mechanism of C/TaC/C composites. The flow velocity of liquid TaC can be deduced by using Darcy's law. The mass ablative rate of C/TaC/C composites is ultimately derived from hydrokinetics and conservation of mass. All these make some helpful discussion for thermal protection materials in the field of astronautics.