High-strength SiC fibre (W core) was fabricated by DC heating chemical vapor deposition (CVD) method. The morphology, microstructure and fracture characteristics of the fiber were characterized by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM). The strength of the fibre was also analyzed by tensile tests. The results show that the CVD-SiC fibre mainly consists of β-SiC. The interfacial reaction layer between W core and SiC layer is 300 nm in thickness and there is great thermo-residual tensile stress, which leads to the tensile strength degradation. High-strength SiC fibre cracking origin is in the W/SiC interfacial reaction zone while low-strength SiC fibre cracking is generated in the inside of W core or on the surface of the fibre. The existence of defects at W core or on SiC fibre surface leads to low tensile strength