Thermal curing process was adopted to improve traditional air-process to reduce the oxygen content of the continuous silican carbide fibers by leading oxygen as less as possible to the fibers during the curing treatment. The polycarbosilane fibers cured by thermal curing are sintered step by step. The condition of sintering process and the element composition, microstructure and properties of the fibers are studied in details by element analysis, SEM,EDX,XRD.