Abstract: When the 30%SiC_p/Al composite materials, with high specific strength and rigidity, are used in the Mars rover, the properties of high toughness and high dimensional stability in the space temperature environment should be considered. In this paper, the space environmental simulation tests are carried out for the aluminum-based silicon carbide composites prepared by the powder metallurgy, to evaluate their adaptability to the space environments in terms of mechanical properties, microstructure, and thermosphysical properties. It is shown that the mechanical properties and the thermo-physical properties vary regularly with the temperature and exhibit anisotropy. The tensile strength is increased and the linear expansion coefficient is decreased with the temperature at low temperature; the impact toughness is increased and the thermal conductivity is decreased with the temperature at high temperature. After the high & low temperature cycling test of the composites, the tensile strength increases, while the residual stress and the anisotropy of the linear expansion coefficient decreases. On this basis, the mechanism of the variations of the mechanical and the thermo-physical properties of the aluminum-based silicon carbide composites under space thermal environment is briefly analyzed.