Abstract: To address the issue of fatigue damage in space-borne fixed parabolic antennas under sinusoidal vibration conditions (e.g., during launch), this study applies Miner’s linear cumulative damage theory. An antenna finite element model was developed, and modal analysis was conducted using the Lanczos algorithm and validated through modal testing. The modal superposition method was applied for both sinusoidal vibration simulations and experimental verification, enabling fatigue life prediction for critical antenna components. The results indicate that all key components’ fatigue damage factors are well below the engineering tolerance threshold of 0.1, confirming the reliability and practical applicability of the proposed approach. This study provides theoretical and practical guidance for fatigue life assessment and structural design of space-borne antennas in complex vibration environments.