In this paper, the time-dependent matrix fracture of carbon fiber-reinforced silicon carbide ceramic-matrix composites (C/SiC CMCs) is investigated considering the interface oxidation. The time-dependent fiber/matrix interface oxidation length and temperature-dependent fiber/matrix interface shear stress in the oxidation and deboned region, interface debonded energy, fiber and matrix modulus and matrix fracture energy are considered in the analysis for the micro stress field, interface debonding criterion and critical matrix strain energy (CMSE) model. The relationships between the time, temperature, applied stress, fiber/matrix interface debonding, and matrix fracture are established. The effects of fiber/matrix interface shear stress, fiber/matrix interface frictional coefficient, fiber/matrix interface debonded energy, and matrix fracture energy on the matrix cracking density and interface oxidation ratio are discussed for different temperatures and oxidation time. The experimental matrix cracking density and interface oxidation ratio for unidirectional C/SiC composite at different testing temperatures and oxidation time are predicted.