Abstract: The geosynthetic reinforced soil (GRS) retaining walls generally exhibit good seismic performance. However, the existing design specifications generally make use of seismic loading parameters that are not totally rational when it comes to the estimation of seismic reinforcement loads. The inaccurate estimation of the seismic reinforcement loads may then result in an unsafe structure and lead to hesitations in the applications of this type of earth structures. In this study, based on the previous research results by the author, a validated finite element approach is employed to analyze the seismic responses of a tall GRS retaining wall under different earthquake loadings. The important influencing factors on the seismic reinforcement loads are pinpointed, which include the frequency characteristics of the earthquake excitation, its intensity and the amplification of seismic motion in the retaining wall. The combined effects are basically determined together by the characteristics of seismic wave propagation and the elasto-plastic properties of backfill soils. The root-square acceleration a_\textrs at the gravity center of the active soil mass in the retaining wall is a proper seismic loading parameter and can be used to estimate the seismic reinforcement loads.