The dispersed SiC-Al powders were prepared by ball milling method and then hot pressed into the prefabricated block, and SiC reinforced YL117 composites were fabricated by semi-solid stirring casting.The microstructure and mechanical properties of YL117 matrix composites were investigated, where the volume fraction of SiC was 3.5%, 4.5% and 5.5%, separately.Subsequently, the 4.5%SiC/YL117 composites with the best mechanical properties were treated by T6 treatment, and optimal solid solution treatment and aging process were obtained.The results show that in case that the volume fraction of SiC was 4.5%the composites presented an uniform distribution of SiC and small size of second phase, the maximum tension strength and elongation, 272.5 MPa and 2.05%, increased by 23.1% and 120.4% with respect to those of matrix alloy, respectively.The agglomeration occured in the matrix when the volume fraction of SiC was 5.5%, which resulted in the decrease of mechanical properties.The optimal heat treatment process was experimentally determined as 500 ℃×4 hsolid solution followed by 170 ℃×10 haging.The microhardness of 4.5%SiC/YL117 composites after heat treatment reached 164.3 HV, increased by 38.9% with respect to that of matrix alloy, tensile strength and elongation, 295.4 MPa and 2.12%, were improved by 33.4% and 128.0%, respectively.