In this paper the internal stresses had been measured on Ti-6Al-4V/7TiC, Ti-3Al-2.5V/7TiC and TP650 composite using the XRD method, the results show no other phases separate out besides the alpha(major phase, for over 90 percent), bate and TiC in the course of heating treatment. Compared the internal stress between prior of heat-treatment and latters, the internal stress was induced in Ti matrix and reinforcement (TiC particles). With temperature of heat-treatment enhancing, internal stress increases gradually, respectively. The relation between the internal stress and strength properties shows the static tensile strength of T64,T32 and T650 developed gradually with compressive internal stress increasing on TiC particle. The compressive stress induced in reinforcement relieved the stress intensity on surface of particle and develops the fracture toughening.