<p>During drilling operations, the tripping-in process of the drill string can easily induce pressure surges, leading to transient pressure fluctuations in the wellbore. These fluctuations may exceed the formation fracture pressure, potentially causing mud loss or wellbore instability. To investigate the characteristics of pressure surges during tripping-in, this study establishes a fluid-structure interaction (FSI) coupling model that integrates drill string vibration with pressure wave propagation in the wellbore. First, considering the initial stress of the drill string, a finite element model for drill string dynamics is developed and solved numerically using the central difference method. Second, transient water hammer pressure models are established for the drill pipe interior, annulus, and open-hole section (without drill pipe), which are solved using the method of characteristics (MOC). The dynamic interaction between drill string vibration and wellbore fluid pressure is realized through the FSI interface at the bottom of the drill string, thereby simulating pressure surge effects during tripping-in. Numerical results indicate that: The pressure surge amplitude increases significantly with well depth, primarily due to the increased compliance of the drill string and compressibility of drilling fluid at greater depths. In deviated wells, drill string vibration is suppressed by friction between the drill string and wellbore wall, leading to reduced pressure surges with higher inclination angles. Pressure surges intensify with higher tripping speeds due to stronger fluid disturbances. The findings provide a theoretical basis for optimizing tripping speeds and assessing pressure surge impacts, offering crucial engineering significance for preventing downhole pressure control failures.</p>