Properties of anti-oxidation and anti-shock of silicon carbide fiber reinforced siliconoxycarbide(Si-O-C) composites were studied through comparing the changes of mass and flexural strength and those of microstructure. The results indicate that SiC_f/Si-O-C composites have fairly excellent properties. The microstructure and properties of SiC_f/Si-O-C composites were analyzed. It has been found that interface structure changes were mainly attributed to the reduction of mass and flexural strength properties.