The finite element model of a pipe bridge structure with large span inverted siphon including support and expansion joint is established. The structural seismic performance of the pipe bridge is investigated using finit element method by examining the influence of supports, expansion joint and water mass in steel penstock on structural seismic response. The large span arch bridge has a significant amplification effect on seismic wave, and the amplification coefficient is within 2-5. Unidirectional sliding supports constrain the lateral displacement of the steel penstock and keep the deformations of the expansion joints and the sliding distance of the supports both within 10 mm, which are beneficial to the seismic resistance of the structure. However, the supports bear large reaction force in lateral direction, which is unfavorable to the design of the supports. Due to the sliding supports and expansion joints, the steel penstock moves like a rigid body under earthquake. The stress of steel penstock is not much affected; but the supporting ring becomes a weakness as it is subjected to notable bending stress. In addition, the huge water mass in the large-diameter steel penstock should also be considered in calculation as it intensifies the structural dynamic response.