During the preparation of continuous fiber-reinforced ceramic materials, the mismatch of linear expansion coefficient between the fiber and matrix may induce thermal residual stresses, which will result in fiber debonding and matrix cracking ultimately. And furthermore, it will have a significant influence on macro-mechanical properties. Based on the unidirectional C/SiC composites, this paper set a unit cell model of "fiber-interface-matrix" to predict the distribution rules of thermal residual stresses by micromechanics method. With ABAQUS software, the numerical simulation research on the preparation of C/SiC composites was developed, which revealed the influence rules of the interface thickness, fiber volume fraction and preparation temperature to the thermal residual stresses of the composites. And the effects of thermal residual stresses on mechanical properties of composites were also analyzed. The result is expected to provide a useful guideline for the design, evaluation and optimal application of C/SiC.