Using the mixed powders of Cu, Ti and graphite, Cf/SiC composite was brazed to Ti-6Al-4V alloy under vacuum condition. The joint microstructures were investigated by X-ray diffractrometry, scanning electron microscopy and energy dispersive spectrometry. The results showed that fine brazed joints of Cf/SiC composite/Ti alloy were acquired at 900~950 ℃ for 5~30 min using Cu-(15~30wt%)Ti with the addition of proper amount of graphite powder as brazing alloy. In-situ synthetic TiC which reduces the thermal stress significantly was obtained during vacuum brazing. TiC reaction layer around surplus graphite and TiC particles in the bonding layer was synthesized by interdiffusing of C element and Ti element in the liquid bonding layer. The reaction rate could be controlled by the diffusion rate of C element from graphite particles to liquid bonding layer.