Abstract: Purpose: Excavation of foundation pits can cause geological losses, alter the stress field of the original soil, induce deformation of the outer layers outside the pit, and have adverse effects on adjacent composite foundations. At present, there is a lack of calculation methods for the interaction between excavation of foundation pits and adjacent rigid pile composite foundations. Method: In view of this, this article proposes a simplified calculation method for the deformation of a single point pile anchor support structure considering the action of a nearby rigid pile composite foundation, based on the proposed method for calculating the active soil pressure outside the pit, combined with the vertical stress mode and deformation characteristics of the single point pile anchor support structure. By discretizing (segmenting) the pile body and using the matrix transfer method, a simplified calculation method for the deformation of the single point pile anchor support structure considering the action of a nearby rigid pile composite foundation is proposed; Result: A theoretical calculation model for composite foundation considering adjacent excavation was established, and the rationality of the calculation method in this paper was verified by comparing numerical simulation with theoretical calculation; Conclusion: Based on the calculated internal forces of the piles, the influence of excavation on the bearing performance of composite foundation piles can be determined. The above research can provide certain theoretical support for foundation pit engineering similar to adjacent composite foundations.