Abstract: The pile-anchor-support composite retaining structure is a complex combination support system for foundation pits. It has many influencing factors, and the current design theory is not mature. Based on an engineering example, through numerical simulation and site monitoring, the force and deformation of the pile-anchor-support supporting structure as well as the influencing factors of deformation are analyzed. The conclusions are drawn as follows: parameters of the retaining piles and anchors, and stiffness of the supports can affect the deformation of the composite retaining structures. To reduce the diameter or increase the embedded depth of retaining piles appropriately can reduce the horizontal displacement of the composite retaining structures. Besides, by increasing the stiffness of the support, the force that supports bears will increase, and the axial force of anchors will decrease. Finally, to increase the anchor spacing or reduce the inclination angle of anchors can increase the internal force of the system.