Three dimensional braided silicon carbide (SiC) matrix composites reinforced with KD-I SiC ifbers (SiC/SiC) are fabricated by precursor impregnation and pyrolysis (PIP) process with a new precursor, LPVCS. The high-temperature flexural properties of the SiC/SiC composites are studied. The results show that the prepara-tion cycles of the composite with LPVCS as precursor are reduced and the density and the porosity are 2.14g/cm3 and 10.8% after 9 cycles precursor impregnation and pyroly-sis processes. At 1300℃ in the air the composite exhibits excellent mechanical properties with the lfexural strength of 470.2MPa and fracture toughness of 20.7 MPa·m1/2. Scanning electron micrographs show that SiC fibers has signiifcant pullout. The fracture surface of the composites show greatly oxidized, and this is the main factor for the decrease of the lfexural strength.%以新型先驱体LPVCS(含乙烯基液态聚碳硅烷)为原料，以经CVD裂解碳（PyC）界面改性的KD-1型SiC纤维作为增强相，采用先驱体浸渍裂解工艺( PIP )制备三维编织SiC/SiC复合材料，并对其室温及1300℃弯曲性能测试表征。试验结果表明，采用LPVCS为先驱体制备SiC/SiC复合材料，降低了材料制备周期，且9个周期后材料密度达到2.14g/cm3，开孔率为10.8%。在1300℃空气环境中，SiC/SiC复合材料弯曲强度达到470.2MPa，断裂韧性达到20.7MPa · m1/2。采用扫描电镜对SiC/SiC复合材料1300℃下断口形貌进行观察，SiC纤维存在一定拔出；断口表面存在较为严重的氧化现象，这是导致材料弯曲强度降低的主要原因。
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