[Purposes] The purpose of this study is to explore the impact of sinking large-diameter open steel pipe piles with hammers at sea on adjacent existing approach bridges, ensuring construction safety and quality, and maintaining the stability of the approach bridges. [Methods] Using high-precision on-site monitoring technology, real-time monitoring of the vibration and displacement deformation of the approach bridge during pile driving process.[Findings] The results show that the existing approach bridge is mainly affected by vertical vibration and horizontal displacement along 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 was revealed. Specifically, in the area near the vibration source, the regression coefficients for pile driving distance and penetration depth are -0.635 and 0.538, respectively, indicating that the vibration velocity gradually decreases with increasing pile driving distance, while the vibration velocity increases correspondingly with increasing penetration depth. On the contrary, 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 trend of vibration velocity change is opposite, that is, it increases with the increase of pile driving distance and decreases with the increase of penetration depth. In addition, the horizontal displacement of the approach bridge also decreases with the increase of pile driving distance, especially for the bridge piers near the vibration source, where the horizontal displacement is more significant. The relationship between the trend of horizontal displacement and penetration depth shows a characteristic of first increasing and then decreasing, especially when the pile foundation enters the rock, the horizontal displacement reaches its peak.[Conclusions] This study provides real-time data support for offshore pile driving construction, revealing the complexity of displacement and vibration under soil structure interaction, and providing scientific basis for safety control and quality assurance of similar projects.