The pseudo dynamic method is one of the most common methods to obtain the earth pressure under seismic conditions. However, this method often ignores the viscoelastic characteristics of the backfill medium and boundary condition with the zero stress on the free surface. In order to remedy the deficiency of the existing pseudo dynamic method, in this paper, the viscoelastic properties of seismic wave propagating medium are considered to improve original pseudo-dynamic methods; Then the calculation formula of the active earth pressure of the inclined retaining wall with overload angle and the fracture angle under the critical failure are derived, and the influences of overloading angle, seismic force coefficient and other parameters on the critical rupture angle and the coefficient of active earth pressure are analyzed. The results show that the critical rupture angle increases with the increase of vertical seismic force coefficient; the horizontal earthquake force coefficient, overloading angle, internal friction angle and retaining wall inclination have great influence on the design of retaining wall.