Polysiloxanes polymer coatings were formed on carbon fiber-reinforced silicon carbide (C/SiC) composites at 100 degrees C in air with barium-strontium aluminosilicate (BSAS) as fillers. After the polymeric coatings were pyrolyzed at 1350 degrees C under argon, a dense SiOC-BSAS-coated C/SiC composite was obtained. The oxidation test in dry air and the corrosion test in water vapor were carried out on the coated composites at 1250 degrees C, respectively. The results indicated that the polymer-derived SiOC-BSAS coatings could protect the C/SiC composites well both in dry air and water vapor. Even after corroded for 200 h in water vapor, the coated C/SiC composites showed little weight loss and high residual flexural strength.