Bridge pile foundations in service are subjected to long-term scour erosion caused by sediment-laden water flow, leading to a gradual expansion of the eroded and worn areas. This in turn results in varying degrees of damage to the pile foundation structure and reduces the durability and safety of the bridge. In order to study the impact of scour erosion on bridge pile foundations, this study took the Hanjiang No. 1 Bridge in Ankang City as the research object. The ANSYS FLUENT software was used to conduct three-dimensional numerical simulations of the pile foundation and analyze the distribution characteristics and patterns of scour erosion under different conditions. The results show that: ① Scour erosion areas are mainly concentrated on the upstream surface of the pile cap, the joint between the pile and the cap, and both sides of the pile shaft; the downstream surface of the cap and the downstream side of the pile shaft experience less erosion. The erosion effect of sediment on the pile foundation is mainly due to impact and cutting; ② Under the same sediment concentration, smaller sediment particle size results in a larger scour erosion area. Increases in flow velocity, sediment particle size, sediment concentration, and pile diameter all contribute to a higher erosion rate, among which flow velocity has the greatest influence. The research results can provide a reference for the design and construction of bridge pile foundations in service.