Steel-bonded cemented carbide GT35 was fabricated from natural ilmenite by in-situ synthesis and vacuum pressureless sintering. The thermodynamics of the synthesis process were analyzed. The results indicated that the stable phases were TiC and iron in the FeTiO3-C system. During the synthesis process, ilmenite was reduced by graphite via a series of titanium oxides to obtain hard phase (TiC) and the steel matrix as the ultimate products. The experimental results shown that GT35 had a reasonable phase composition and fine TiC particles embedded uniformly in the steel matrixes. The composites exhibited excellent mechanical properties: the relative density was higher than 97%, the hardness reached HRC 61.5 and the maximal bending strength was about 1270MPa.