The utility model relates to a pier protection device. The pier protection device comprises at least one anti-collision structure and a connecting structure used for connecting the adjacent anti-collision structure or the anti-collision structure and a pier. The anti-collision structure comprises an outer-layer head-on collision structure, a middle energy absorption supporting structure and an inner-layer protection structure. The middle energy absorption supporting structure is of a negative poisson ratio structure formed by arranging multiple layers of energy absorption units in a crossed mode according to a certain rule, each energy absorption unit is in an inwards-concave hexagon shape and comprises a set of oppositely-arranged side plates and a set of oppositely-arranged inwards-concave folded plates, and the included angle between each side plate and the corresponding inwards-concave folded plate is smaller than 90 degrees. The anti-collision structure has the characteristic of negative Poisson's ratio, the energy dissipation time is prolonged, the deformation degree of the energy absorption material is increased, the protection effect on overwater buildings such as piers isgreatly improved, and the structural stability is also enhanced; the energy absorption units are periodically arranged, the structure is simple, the production process is simple, the product quality is easy to control, the anti-collision effect can be improved, and the manufacturing cost is saved.