The objective of this study is to prepare CNT/AlSi10Mg composites using mechanical ball milling combined with SPS. The study investigates the influence of ball-milling time and CNT content on the mechanical and corrosion resistance of the composite. This is performed to address the challenge of CNTs dispersion and to understand how CNTs impact the mechanical and corrosion resistance of the composites. The morphology of the composites was characterized using scanning electron microscopy (SEM) transmission electron microscopy (TEM) and Raman spectroscopy, and the mechanics and corrosion resistance of the composite materials were tested. The results demonstrate that the uniform dispersion of CNTs can significantly enhance both the mechanical properties and corrosion resistance of the material. Specifically, when the ball-milling time was 8 h, CNTs were uniformly dispersed in the Al matrix. The CNT/AlSi10Mg composite shows the best interfacial bonding when the mass fraction of CNTs is 0.8 wt.%, with a tensile strength of −256 MPa. This is 69% higher than the original matrix material without the addition of CNTs. Moreover, the composite exhibited the best corrosion resistance.