Abstract: For three-dimensionally braided C/SiC composites,the tensile and compress experiments were carried out to get main mechanical characters, damage development and failure mechanisms under tensile and compress loads. The elastic properties and failure characters under two kinds of loads were compared and some experimental conclusions were deduced. It can be concluded from the stress-strain curves of the test that the damage development in three-dimensionally braided C/SiC composite specimens is continuous. The test results also reveal that the tensile modulus is less than the compress modulus and the tensile stress is greater than the compress stress. The acoustic emission data can reveal the damage development in C/SiC specimens.