Many slopes of subgrades fail during earthquakes.Therefore，it is necessary to evaluate the stability of slopes under seismic loading in the design of the subgrade.The pseudo-static method is one of the most frequently used methods in seismic stability analysis of slopes and is the specified method in the “Specifications of Seismic Designs for Highway Engineering.” One of the key factors in this method is the effect of amplification of the peak acceleration of a seismic load.To study this effect，a large-scale shaking-table model was developed with a subgrade model at a scale of 1:20.A series of tests was performed with various inputs of seismic wave type，amplitude，and frequency.Seismic wave type included one type of artificial-seismic wave （sinusoidal wave）and two types of observed seismic waves （EL Centro and Wenchuan seismic waves）.The amplitude and the frequency of each wave were determined by the scales of model similarity.In these tests，accelerometers were set at various locations in the subgrade model.Accelerations of the model under seismic loading were then measured in both vertical and horizontal directions.Amplification coefficients were calculated by dividing these accelerations by the measured acceleration at the surface of shaking-table.Test results show that horizontal seismic waves are greatly amplified by the subgrade；amplification of vertical seismic waves was not noticeable.Maximum amplification coefficients of 2.45 and 1.3 were located at the surface of the slope for both vertical and horizontal waves，respectively.The amplification coefficient of the horizontal seismic wave varied along the height of the subgrade and was divided into three stages of height increase such as increasing，decreasing，and later increasing again.The maximum amplification coefficient was reached at the highest point of the pavement，and it varied along the pavement.The amplification coefficients were greater at the surface of the slope than those inside for both horizontal and vertical seismic waves.For horizontal waves，the amplifications differed significantly under seismic waves with different frequencies，wave type，and amplitude.The amplification coefficient increased with an increase in frequency in the test.For the three types of input waves，the amplification coefficient was maximum under EL Centro seismic waves and minimum under sinusoidal waves.Moreover，the amplification coefficient decreased with an increase in amplitude.These results show that the amplification varies under different seismic loads and should be evaluated according to actual situations.Further，these results are helpful for determining seismic load in the seismic stability design of subgrades.