[Purposes] This study aims to explore the influence of large-diameter open-ended steel pipe sinking piles with hammers at sea on adjacent existing approach bridge, ensuring construction safety and quality while maintaining the stability of the approach bridge. [Methods] High-precision on-site monitoring technology was employed to real-time monitor the vibration and horizontal displacement of the approach bridge during the pile sinking process. [Findings] The existing approach bridge is mainly affected by vertical vibration and horizontal displacement in the bridge direction, especially the bridge piers near the vibration source, where the response is more significant. Through multiple linear regression analysis, the complex relationship between the peak vibration velocity and the pile driving distance and penetration depth is revealed. Specifically, near the vibration source, the regression coefficients for pile driving distance and penetration depth are ?0.635 and 0.568, respectively, indicating that the vibration velocity gradually decreases with increasing pile driving distance while increasing correspondingly with increasing penetration depth. Conversely, in the area far away from the vibration source, the regression coefficients of pile driving distance and penetration depth are 0.678 and ?0.422, respectively, indicating that the vibration velocity increases with the increase in pile driving distance and decreases with the increase in penetration depth. In addition, the horizontal displacement of the approach bridge also decreases with the increase in pile driving distance, especially for the bridge piers near the vibration source, where the horizontal displacement is more significant. The horizontal displacement exhibits a trend of first increasing and then decreasing with penetration depth, reaching its peak when the pile foundation enters the rock. [Conclusions] This study reveals the complexity of displacement and vibration under soil-structure interaction, providing real-time data support for offshore pile sinking construction and offering a scientific basis for safety control and quality assurance of similar projects.