SiCp/Z101 composites substrate can be successfully fabricated by pressureless infiltration of ZL101 alloy liquid into porous SiCp preform, the relative density are nearly up to 99%. This is mainly because that generated SiO2 phase on the surface after sintering of SiCp not only has joint function to the porous of SiC perform, but also obtains two-phase wetting between SiC and Al matrix through the interface reaction, resulting in promoting spontaneous infiltration. SiC preforms have almost no change of shapes and sizes after infiltration of Al liquid and can achieve near-net-shape of the composites for substrate. Volume fraction of SiC can be effectively improved by using binary mixture particles with the diameter ratio of 11:1, through which the properties of substrate can be controlled effctively. By the addition of SiCp, strength of the composites is improved remarkably, and its elastic modulus increases correspondingly about one time, the increase of SiC volume fraction can markedly reduce coefficient of thermal expansion (CTE) of composites , but meanwhile decrease thermal conductivity(TC) of composites, and its TC (at 50 °C ranges from 120.7 W/(m•k) to 99.4 W/(m•k) and its mean linear CTE (25°C to 50°C ) ranges from 9.47×10−6 k-1 to 7.05×10−6 k-1 as volume fraction of SiC ranges from 38% to 68%.