A dredging ship was drifted by flood after dragging the anchor and collided with the bridge pier of the non-navigation hole of the Xunjiang Grand Bridge. According to the investigation of the hydrometeorological conditions, the drifting ship state, the damage status of the accident and the exterior appearance of the damaged bridge pier, the ultrasonic opposite measurement method and the reflected wave method were used to detect the internal damage of the impact area of the concrete bridge pier and the integrity of the pile foundation, and ABAQUS was used to calculate the stress, displacement and damage distribution of the bridge pier under the action of the impact of the drifting ship after dragging anchor to analyze and judge the damage status of the bridge pier in the accident, which provides a technical basis for the subsequent processing. The results show that there was no cracking and obvious damage at the collision of the pier, the connection between the pier and the cover beam was intact, and the upper structure was normally shelved on the pier. There was no obvious damage inside the concrete in the collision area, and the structure of the pile body was intact without obvious defects. High-risk damage existed at the upper left and lower right joints of the beam at the variable diameter area. There was a huge difference between the impact of ship anchoring and ship drifting on the pier, and it can be concluded that the collision did not cause damage to the structure of the pier.