Seismic effects may cause destruction，such as soil liquefaction，losing of slope stability and settlement of foundation. Certain connections are embodied in these forms of destruction，and the accurate liquefaction calculation is crucial and fundamental to the analysis of seismic effects. We compare the common liquefaction evaluating methods，such as the code method and simplified method etc to analyze the applicability and accuracy of these methods，determine the strength degradation in soils through the liquefaction extent to incorporate in the calculation of slope stability，and combine the three forms of destruction to analyze the influence of seismic effects on the bank slope by an engineering example. The results show that the strength loss and settlement of soil are closely related to the degree of liquefaction. The soil parameters under seismic load level should be used in slope stability analysis，and separate calculation methods of seismic settlement should be determined according to the liquefaction potential.