Abstract: Using the new shoulder balance weight retaining wall of an old embankment widening project of a mountainous highway as the prototype, four groups of geotechnical centrifugal model tests are designed based on the wall motions under translation (T), rotating around base (RB), rotation around top (RT) and T+RB modes, the impact of wall motion modes on earth pressure and deformation of the filling is discussed, and the process of soils at various depths entering in to the active earth pressure is analyzed. The results show that: (1) The wall motion modes almost have no influence on the values and distribution of earth pressure on the upper wall, but when the ratio of displacement to height of retaining wall is less than 0.3%~0.5%, the shallow layer fills behind the upper wall have soil arching effect which is caused by wall-soil friction, and the coefficient of horizontal earth pressure increases; (2) The equilibrator has a shadowing effect on the down wall earth pressure, and the influence area is about 1/3 height of the down wall below the equilibrator. The results reduce the position of the acting point of earth pressure resultant force; (3) The motion modes have obvious impact on the fill settlement. When the maximum wall displacements are the same, the fill settlement of the T mode is significantly larger than that of the RB and RT modes. Under the RT mode, although it has the same displacement area as the RT mode, the equilibrator deflects downward. The fill settlement is promoted, leading to that the fill settlement of the RT mode is larger than that of RB mode, and the second fracture surface occurs easier on the upper wall.