Abstract: Many retaining structures of slopes are destructed by the Wenchuan earthquake. Seismic design must be reconsidered. Based on the performance of the slope, a supporting structure seismic design is proposed. The slope retaining structure seismic design should be in accordance with the requirements of the three-level fortify rules. They are as follows: a more severe earthquake, the slope in steady state, stability coefficient 1.2. Experience design earthquake, in stable state, the slope stability coefficient is 1.15. Confronted with severe earthquake, the slope in basic unstable state, the stability coefficient is 1.05. Using the seismic design principles, combined with strength reduction dynamics analysis method, a slope seismic design is given for example. The results show that the method proposed in this paper is simple to apply, and can be of great importance for slope structure seismic design.