The mechanical properties at high temperature of Si3N4/BN fibrous monolithic ceramics were tested. The flexural strength of SiC whisker reinforced Si3N4/BN fibrous monolithic ceramics from 25 degreesC to 1200 degreesC were investigated. The strength degraded slowly from 1000 degreesC to 1200 degreesC which was different to Si3N4 monolithic ceramics. The creep behaviors of the material at different temperatures were characterized. Si3N4/BN fibrous monolithic ceramics possess high creep resistance. The chemical composition and microstructure of the composites were analyzed by XRD and SEM.