The in situ reaction procedure and microstructure evolution of a graphite fiber reinforced Ti-Al composite (Grf/Ti-Al) was investigated, and the stability of TiAl_3 at high temperature was discussed. As-cast material was prepared by pressing molten pure aluminum into a preform, which was composed of titanium particles and graphite fibers. The in sire reaction procedure of the as-cast material was investigated by dif-ferential scanning calorimetry (DSC), and phases in the products were detected by X-ray diffraction (XRD). Experimental results showed that TiAl_3 was formed first. With an increase in temperature, TiC and Al_4C_3 were observed, but TiAl_3 decreased. In the final product, Al_2O_3 and TiO_2 were observed. It was considered that the previous forming TiAl_3 decomposed, then TiC precipitated, and subsequently, oxidation resulted in the formation of Al_2O_3 and TiO_2.