Based on a domestic automobile engine, a new aluminum matrix SiC composite was designed and the influence of preparation technology on the properties of composite was analyzed. The results show that 730 ℃ stirring temperature and 17.5% SiC content can obtain the best sample. The tensile strength of sample is 352 MPa, the yield strength is 334 MPa, the fracture elongation is 0.52%, the Vickers hardness is 1 724.8 N/mm², the linear wearing capacity is 0.016 mm, and the thermal conductivity is 121 W/(m·K). The stirring temperature has a significant effect on the strength of composite, and the addition of SiC has a great effect on the fracture elongation, Vickers hardness, wear resistance and thermal conductivity. The analysis results of phase composition show that the optimal phase composition of sample is Al, SiC and Si. The microstructure shows that the aluminum alloy matrix material is distributed in a continuous network, which is beneficial to improve the mechanical properties of composite. The material has good comprehensive properties and is more suitable for cylinder block material under complex loads.