Aseismic analysis on the aqueduct across the Yellow River was conducted by 3－D FEM under different working conditions. The aqueduct adopted double U－shaped section. The vibration frequencies, corresponding modal vibration shapes, and dynamic respones of the structure based on two spectrums,i.e., one was provided from the specifications for seismic design of hydraulic
structures and the other was obtianed from earth risk analysis of the field, were calculated. The results showed that: the influence of the water body in the aqueduct on vibration characteristics of the aqueduct is distinct; the dynamic respone calculated from the field is about 3 times that defined by specifications; the supporting structure is the weak position of the aqueduct.