Aluminum (Al) is one of the materials with superior properties, so it is often used as the main component in manufacturing. Depending on the composition, adding silicon (Si) can strengthen or weaken the mechanical properties. This research focuses on the importance of developing lightweight and strong materials to meet the needs of the automotive and manufacturing industries, where AlSi alloys have the potential to excel in terms of strength and corrosion resistance. The variation in Si concentration used in the study was 0%, 5%, 10%, 15%, and 20%. Molecular dynamics simulations were performed to observe changes in the mechanical properties of their main tensile strength, compressive strength, and elasticity modulus, and visualize atomic structures (FCC, BCC, HCP, and irregular) before and after deformation. The test results showed that the increase in Si content tended to decrease the values of maximum stress, yield stress, and modulus of elasticity in both tensile and pressure tests. In addition, the dominant FCC crystal structure in the Al metal decreased. At the same time, the number of irregular atoms increased, which indicates an irregularity in the crystal structure due to the addition of Si. This study concludes that the addition of high amounts of Si reduces the stability of the crystal structure and mechanical properties, so an optimal composition limit is needed so that the material remains suitable for engineering applications. This research helps select Al-based alloy materials for components that require high tensile and compressive strength and good structural stability.