Abstract: A continuum damage constitutive model of 2.5D C/SiC composites containing both tensile and shear damage variables were established based on continuum damage mechanics. Tensile and shear tests were conducted to obtain the stress-strain curves, and the test curves were fitted to obtain parameters of damage variable evolution. The constitutive model was then embedded into commercial finite element software ANSYS by subroutine technology and the finite element method was used to calculate the stress-strain curves of materials. The coupling effect of tensile and shear damage was considered. The stress-strain curves under off-axis tensile condition was calculated. The results show that the stress-strain curves along warp and weft direction tensile and in-plane shear agree well with the test results and the maximum deviation are respectively 4.30%, 3.09% and 3.73%; the calculated off-axis tensile stress-strain curve is also consistent with the test data.