In order to study the dynamic responses of geosynthetic-reinforced retaining soil wall with consideration of seismic time history, a finite difference numerical model of 6m high geogrid reinforced soil retaining wall was built based on the software FLAC. The soil was modeled using Mohr-Coulomb constitutive model and the reinforcement material was simulated using the Cable unit provided by software FLAC. The rationality of numerical model was verified by the shaking table tests carried out at Royal Military College of Canada. The accelerating time, the accelerogram and the peak accelerations were considered. The comparisons of numerical simulation results with the results obtained on the current Chinese Specifications for Design of Highway Reinforced Earth Engineering and on the FHWA design guidelines were processed. The results show that the remarkable effects of the accelerating time of the seism can increase tension force of the geogrid-reinforcement and lateral displacement of the retaining wall. Acceleration amplification which increases with the height of the reinforced retaining wall exists significantly. Thus the traditional Quasi-static seismic design methods only using single seismic coefficient may be lack of rationality for the reinforced soil retaining wall with larger height. The influence of time history of seismic acceleration should be fully pay attention in the design.