With a deep excavation pit as an example, FLAC^3D is employed to simulate the trends of active earth pressure in the presence of lateral displacement of retaining wall in consideration of the joint action among retaining wall, beam and soil mass. The active earth pressure distributes in “R” shape when drum-type displacement of retaining wall occurs. Furthermore, the influences of several parameters (including internal friction angle, cohesion, embedded depth of retaining wall, aspect ratio of excavation pit) on the lateral displacement and active earth pres-sure are analyzed. Results reveal that internal friction angle and cohesion of the soil have great influences on the lateral displacement of retaining wall. With the increase of internal friction angle and cohesion, the active earth pressure and the lateral displacement of retaining wall decrease gradually. The embedded depth of retaining wall has no obvious effect on active earth pressure, but affects the lateral displacement: the lateral displacement of the upper retaining wall increases gradually when the embedded depth of retaining wall is increasing; while for the lower part of the retaining wall, the regularity is the opposite, with the lateral displacement reaching the minimum when insert ratio is about 1.2. Above the excavation face, the active earth pressure on the retaining wall decreases gradually with the increase of aspect ratio; while below the excavation face, especially near the bottom of the retaining wall, the active earth pressure on the retaining wall gradually increases with the increase of aspect ratio.