Abstract: The diecasting TiC/Al-9Si-1.4Cu-0.5Mg composite formed by melt in situ reaction technique has been successfully fabricated. The tensile properties of the composites were tested. The results have shown that the ultimate tensile strength of the diecasting 5%TiC/Al-9Si-1.4Cu-0.5Mg composite was 354 MPa and 272 MPa at room temperature and at 260℃ respectively, 26% and 46% increases over the values of unreinforced alloy (280 MPa and 186 MPa) respectively. The tensile elongations of the 5%TiC/Al-9Si-1.4Cu-0.5Mg composite at room temperature and at 260℃ respectively are near upon those of unreinforced alloy. Finally, the way of further improving the strength of TiC/Al-9Si- 1.4Cu-0.5Mg composites is also discussed.