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The SiC fiber tensile strength and mechanical properties of 2D-SiCf/SiC composites, the fiber surface morphology, composite fracture surface morphology and composite interface characteristics before and after removing carbon coating were analyzed and characterized by bundle tensile test, three-point bending test, SEM and HRTEM. The results show that inherent defects on the surface of SiC fiber are exposed after the carbon coating removal, and the tensile strength of SiC fiber decreases by about 15%. The flexural strength of 2D-SiCf/SiC composites after the carbon coating removal is only 30 MPa, which is the 1/6 times of that of composites prepared by the original fiber. The fracture surface of 2D-SiCf/SiC composites after the carbon coating removal is very even, which proves the fiber reinforced effects to be poor. The analyzed results indicate that because of the increase of defects after the carbon coating removal, the interfacial physical bonding strength and the fiber physical damage will all increase. At the same time, after the carbon coating removal, the chemical action active centers and the oxygen contents on the fiber surface will increase, the situation of that will bring about the interfacial chemical bonding strength and the fiber chemical damage increasing, which has been proved by HRTEM test. The strongly bonded interface and serious fiber damage result in the mechanical properties of 2D-SiCf/SiC composites degrading badly after the carbon coating removal.