In order to reduce the error between the classical Coulomb’s earth pressure theory and the vertical layered earth pressure in actual engineering, based on the traditional Coulomb’s earth pressure theory and finite earth pressure theory, and considering the strength characteristics of unsaturated soil, the static equilibrium relationship of layered soil behind the retaining wall was established. The calculation formula of the active earth pressure of the vertical layered soil was obtained. By comparing with the existed theories, the reasonableness of the method in this paper was explained. The influence law of the filling property parameters and the retaining structure geometric parameters on the earth pressure are respectively analyzed. The research results show that the difference of the vertical soil layer has a great influence on the calculation result of active earth pressure. The active earth pressure of vertical layered unsaturated soil decreases with the increase of effective cohesion, effective internal friction angle and matrix suction, and increases with the increase of the grading angle of back wall and the slope angle of backfill surface. The change of the shear strength indexes of the filling near the back wall has a more obvious influence on the active earth pressure.