Abstract: There are some inadequacies in the current elastic foundation beam theory about deep excavation protected design. In current practice, the influence of the protecting structure displacement on the earth pressure behind the retaining wall is neglected and linear displacement in front of the retaining wall is assumed. This is not true in reality and also the calculating parameter m cannot be decided easily. Based on the P-y curve equation of horizontal load piles, a new earth pressure calculation model is put forward, in which the nonlinear influence of the protecting structure displacement on the earth pressure is considered. Furthermore, the calculating parameters are studied in detail. The results of test show that the new model agrees with the fact well, and the calculating parameters can also be obtained conveniently.