Infiltration-in situ reaction synthesis of Cf /TiAl3 composite was investigated. The as-cast material was obtained by titanium particles, carbon fibers and pure aluminum. Titanium particles and carbon fibers were mixed and pressed to form a preform firstly, and then molten pure aluminum was pressed into the preform, subsequently, cooled rapidly. In situ reaction samples were obtained by heating the as-cast material from 600 to 1000 °C for 1 h. The microstructural evolution of in situ reaction samples was analyzed by scanning electron microscopy and energy dispersive X-ray. In addition, the phase composition of products was inspected by X-ray diffraction. Experimental results showed that the dominant product of TiAl3 and a small amount of Al4C3 were formed at low temperature. While TiAl3 was not stable at high temperature, along with its decrease, TiC phase became favorable. In the final products, TiAl3 , TiC and Al4C3 were detected. Thus, the in situ reaction for Ti-Al-C system composite proceeded a formed-decomposed-precipitated mechanism. Infiltration-in situ reaction synthesis of Cf / TiAl3 composite was investigated. The as-cast material was obtained by titanium particles, carbon fibers and pure aluminum. Titanium particles and carbon fibers were mixed and pressed to form a preform first, and then molten pure In situ reaction samples were obtained by heating the as-cast material from 600 to 1000 ° C for 1 h. The microstructural evolution of in situ reaction samples was analyzed by scanning electron microscopy and Energy dispersive X-ray. In addition, the phase composition of products was inspected by X-ray diffraction. Experimental results showed that the dominant product of TiAl3 and a small amount of Al4C3 were formed at low temperature. While TiAl3 was not stable at high In the final products, TiAl3, TiC and Al4C3 were detected. Thus, the in situ reaction for Ti-Al-C system compos ite proceeded a formed-decomposed-precipitated mechanism.