Abstract: Site condition can affect amplitude and spectrum characteristics of seismic ground motion. Adjustment scheme for ground motion characteristic period of response spectrum in Current Seismic Ground Motion Parameter Zonation Map of China was given but peak ground motion and platform value of response spectrum were not taken into account. Illustrated by the example of Chengdu basin, engineering borehole data in the basin region were extensively collected. In consideration of the large difference between different engineering geological divisions, the equal linear method was used to conduct seismic response analysis of soil layers for different boreholes based on engineering geological division. As a result, suggested earthquake ground motion adjustment factors for different engineering geological divisions were given.