Abstract: Enhancing the impact resistance of equipment under complex shock environments is critical for ensuring operational stability. Owing to its excellent vibration damping properties, metal rubber has been widely used in impact-resistant applications. In this study, shock tests were conducted on a two-stage vibration isolation system based on metal rubber. A shock test platform was established, and semi-sine wave excitation was applied to investigate the effects of shock amplitude, duration, and the densities of the two metal rubber stages on the system’s impact resistance. The performance was evaluated using shock isolation coefficient and kinetic energy attenuation rate as indicators. The experimental results show that increases in shock amplitude and duration both degrade the impact resistance performance of the system, with shock amplitude having a more significant effect. Furthermore, a synergistic mechanism was revealed between the density matching of the two metal rubber stages and the system's energy dissipation capacity. A higher density in the first-stage metal rubber leads to better impact resistance, while a lower density in the second-stage enhances energy dissipation. The results indicate that when the first-stage density is 1.75 g/cm³; and the second-stage density is 1.4 g/cm³, the system exhibits optimal impact resistance, with a kinetic energy attenuation rate as high as 85.71%. These findings provide theoretical and engineering guidance for the design of metal rubber-based two-stage vibration isolators in complex shock environments.