In this article, the problem of determining pseudodynamic pressure and its associated forces on a rigid vertical retaining wall is solved analytically using the horizontal slices method for both reinforced and unreinforced walls. The use of this method in conjunction with the suggested equations and unknowns offers a pseudo-dynamic method that is then compared with the results of an available software. In the proposed method, different seismic accelerations have been modeled at different soil structure heights. Reinforced soil pressure on a retaining wall and the angle of the critical failure wedge are calculated using the new formulation. It is shown that as the horizontal seismic acceleration coefficient increases the angle of the critical failure wedge is reduced and that the maximum extension force can be increased for each layer by using stronger and longer reinforcements. The results of the pseudo-dynamic method show that both vertical and horizontal seismic accelerations are essential coefficients for calculation of the required length and extension force of the reinforcements and that their importance increases as the vertical and horizontal seismic accelerations increase. Also, the location of the application point of the resultant pressure rises as the horizontal seismic acceleration coefficient increases.