Abstract: The effects of soft interlayer within some rock sites on seismic response of ground surface are rarely studied. The effects of the depth, thickness and shear velocity of soft interlayer within rock sites on surface peak acceleration are analyzed using one-dimensional equivalent linear method of soil seismic response on the basis of the wave motion model. Primary results show that the intensity of input ground motion doesn’t change the laws of the effects of the depth, thickness and shear velocity of soft interlayer within rock sites on surface peak acceleration, and that the varying laws of surface peak acceration affected by the depth, thickness and shear velocity of soft interlayer are controlled by the comprehensive influences of the three factors.