In order to evaluate the interfacial reaction, a SiCf/Ti (TA1) composite was fabricated by a vacuum hot pressingmethod and then heat-treated in vacuum at 800℃ for up to 100 h. The elemental distributions of C, Si and Ti at theinterfacial reaction zone were investigated. It was found that the reaction zone occurs during the fabrication processand continuously grows at high temperature because the Si and C atoms diffuse from SiC fibers to the matrix and Tiatoms diffuse in the opposite direction. The growth of the reaction zone is diffusion controlled and the mechanismof the reaction can be described by a reactive diffusion model of solid-state growth of an AmBn layer between twoelementary substances A and B.