Due to heavier traffic loads, progressive structural age, and corrosion of steel reinforcement, there has been an increasing need to strengthen the pile foundation of concrete bridges. In this paper, the damages and deteriorations on a concrete bridge in Guangzhou City are described in details, which causes are discussed also. The rehabilitation method by prestressed cushion cap is proposed based on the finite element analysis. The rehabilitation scheme is verified by the result of calculation, and the practice of strengthening project proves that this method is technical feasibility, construction convenience and lower economic cost. The research results can be provided as a reference for the similar bridges.