SiCp/Al is one of the critical materials for lightweight manufacturing of large aerospace structural components. However, its multi-phase heterogeneous characteristics lead to severe machining damage and challenges in surface quality control. This study conducts tensile tests across a wide temperature range from -196 to 20°C, revealing the evolution of mechanical properties dominated by cryogenic strengthening effects in SiCp/Al materials. Comparative experimental studies on cryogenic and room-temperature milling are performed to analyze the macro-micro mechanisms of material cryogenic characteristics and process parameters on cutting forces and surface integrity. The results demonstrate that the material exhibits higher yield strength and tensile strength in cryogenic environments, while liquid nitrogen cooling reduces cutting temperature and weakens local thermal softening effects, resulting in greater milling forces compared to room-temperature machining. However, as the cryogenic cooling enhances the interfacial strength of the material, it reduces the extent of surface pits and crack damage during milling, producing better surface roughness than conventional processing. This research provides a novel theoretical foundation and engineering basis for precision manufacturing of difficult-to-machine aerospace composites.