The lateral displacement of passive soil induced by the excavation of existing buildings has significant impact on the bearing capacity of foundation piles within the pit. The load-bearing characteristics of foundation piles under the lateral movement of the passive soil were investigated through indoor model experiments. Focus was paid on the influences on the pile’s bending moment and shear force of a few factors such as the spacing between retaining and foundation piles, the excavation depth, the axial loading level at the top of the pile and the height of cap restraint. Results showed that under the cantilevered supported excavation condition, the displacement pattern of the passive soil resembled an inverted triangle. The bending moment and the shear force of the foundation pile had several heterogeneous peaks distributed along the pile. Based on this, the foundation pile from top to bottom was divided into three sections, i.e. the excavation-exposed section, the passive-load section and the active-effect section. The smaller the distance between the supporting and foundation piles and the deeper the excavation depth, the greater the bending moment and the shear force induced along the foundation pile. The coupling effect of axial loading and lateral displacement will further increase the bending moment of the foundation pile. The change of the height of the pile top restraint will affect the bending moment and the shear force of the pile. With other conditions being the same, the greater the height of the pile top restraint, the smaller the bending moment and the shear force of the pile. The research results can provide support for the engineering design of underground-storey supplement.