In this paper, Ti-1100 composites reinforced with TiB+TiC ceramic particles were fabricated using in situ technologies. Mechanical properties of the composites with different volume fractions of TiB and TiC reinforcements were evaluated by tensile tests at 873K. The breakage of TiB was observed during the failure process of the composite. Strengthening efficiencies of the reinforcements for different composites were calculated. The strengthening mechanisms in this composite during tensile tests were discussed. It was suggested that the effect of the solution of C, which was produced in the preparation process, also can not be ignored for such a composite.