Abstract: The response plate impact system is a critical testing apparatus for evaluating spacecraft components under pyroshock environments. However, the unclear relationship between system parameters and dynamic response characteristics often results in inefficient test calibration. To address this issue, a high-fidelity finite element model of a double-layer response plate system was developed. A systematic parametric study was conducted to investigate the effects of key parameters—such as lower plate thickness, upper plate mounting position, projectile impact location, and impact velocity—on the shock response spectrum (SRS). The results demonstrate that: 1) In the low-frequency range (≤1000 Hz), the SRS amplitude decreases approximately linearly with increasing lower plate thickness, reaching only 25% of the baseline value at 21 mm; 2) When the projectile impacts near the supporting studs, the mid-to-low frequency SRS (≤5000 Hz) is amplified by up to 2.2 times; 3) Mounting the upper plate closer to the boundary constraints reduces low-frequency response amplitudes by approximately 50%; 4) Increasing the projectile velocity from 6 m/s to 18 m/s amplifies the low-frequency response by a factor of 5.5, while the characteristic frequency of the SRS curve (around 1500 Hz) remains relatively stable. These findings provide quantitative insights for optimizing design parameters and enhancing the efficiency and reliability of impact test systems in spacecraft shock response evaluation.