Abstract: The mass loss of thermal protection material under the condition of high temperatures , enthalpies andpressures is caused by physical , chemical and mechanical factors and the change of material thermomechanical properties and thermophysical properties at high temperatures is irreversible , showing complex nonlinear characteristics.The present paper is devoted to the development and establishment of corresponding thermochemical and thermomechanical ablative models by analyzing flow and C/ C composite materials ablative mechanism. With the help of theconservation law of mass and energy and thermochemical equilibrium of system chemical reaction , the thermal conduct equation is presented based on a moving boundary caused by linear ablation ; the mathematical equation is solvednumerically by a nonlinear coupling scheme , while the changes of material properties with temperature are considered. The calculated result s characterize the dynamic thermomechanical behavior of the material in special environments such as high temperature. This analysis accords well with experimental data. The analysis realizes instantane2ous simulation of ablation effected by complex coupling factors of high temperature and load.