Abstract: As a new type of bridge pier structure, gabion pier is characterized as environmental friendly and low cost, but flood damage accidents are inevitable in practical engineering application. Taking a mountain gabion bridge for example, model test and numerical simulation were used to research the flood damage mode of gabion pier scouring from sediment erosion form and flow field. The results show that horizontal displacement perpendicular to the flow direction and leaning forward of pier resulted by erosion are the main causes of destruction; on one side of the bridge pier，the scouring width at pier tail is equal to pier width,the distance from the point of maximum scoured depth to pier foundation is 0.1~0.15 times of pier width; the concentrated force on the front of the pier seriously threatens the general safety of the bridge.