The protection of sacrificial piles is one of the main measures to reduce the local scour on bridge piers. Existing research on the protection of local scour by sacrificial piles mainly focuses on circular sections and pays less attention to the influence of the section characteristics of sacrificial piles on local scour. In this study, physical model experiments with sacrificial piles of different diameters and cross-sections were carried out to protect a single bridge pier from local scour in a unidirectional flow circulating flume. During the experiment, the development of the local scour depth and the shape of the scour pit at the scour balance were accurately measured by an underwater high-definition camera and tilt photogrammetry. The study investigated the influence of sacrificial pile diameter and section shape on the protective effect of sacrificial piles for a single pier against local scour. The results show that the diameter and section shape of the sacrificial pile are key factors affecting the local scour protection effect of the bridge pier. The protective effect of the sacrificial pile on the rear pier increases with increasing diameter of the sacrificial pile. Compared with square and circular cross-section sacrificial piles, rhombus section sacrificial piles have a better scour protection effect on bridge piers. The sacrificial pile protection will affect the severity of the scour pit change around the rear pier, and the better the protection effect is, the gentler the change is in the rear scour pit. Additionally, the protection of the sacrificial pile shortens the time for the scour to reach the equilibrium state, and the larger the diameter of the sacrificial pile, the shorter the time is to reach the scour equilibrium state. Therefore, when using sacrificial piles to protect against local scour of bridge piers, the section characteristics of sacrificial piles should be reasonably considered to improve the scour protection effect.