Abstract: The displacement and the relevant reliability of a pile beneath column-supported bridge are investigated. Firstly, the bearing characteristics of the bridge pile in mountainous area are analyzed, and its differential equations are established and solved, by which the internal force and displacement along the pile shaft are obtained. Secondly, the main influence factors for the horizontal displacement are analyzed. Based on the displacement distribution solved by the limit state equations, the reliability index and failure probability indexes are solved by the checking point method. Finally, an real case of a bridge pile is analyzed by the proposed method, and the results agree well with those of the improved response surface method and Monte Carlo method.