<p>This study designed a yielding pile consisting of a buffer material layer and a rigid pile. To calculate its lateral earth pressure, the ‘yielding pile–sliding body’ composite system was simplified to a ‘retaining wall–buffer material–soil’ composite system. The deformation mechanism of the cushioning materials and soil was analyzed based on elasticity theory, using the tangent modulus in the Duncan–Chang model as the soil elastic modulus. The relationship between earth pressure and the compression of the buffer materials was established, and the lateral earth pressure expression of the pile was derived (Method 1). The deformation characteristics of the cushioning materials were assumed to be consistent with three typical retaining wall displacement modes: horizontal translational displacement (T), rotation around the wall top (RT), and rotation around the bottom wall (RB). On this basis, three methods for calculating the lateral earth pressure of the yielding anti-slide piles are proposed (Method 2-T, RT, and RB). The deformation of the soil and cushioning materials is consistent with the retaining wall’s horizontal translational displacement. The results of Method 2-T align well with the measurements in the middle and upper part of the compressed pile.</p>