The seism response analysis of aqueduct bridge is analyzed with modal superposition method based on response spectrum which participant mode of vibration chooses the former 1 0 steps and combinatorial method was srss 渡槽的地震反应分析采用振型分解反应谱法,参与振型取前10阶,组合方法用srss法,求得结构的地震作用效应。