To address the response of adjacent piles caused by foundation pit excavation， this study first adopts the image source method to deduce the calculation expression for the soil free displacement field around a foundation pit from the deformation curve of the retaining wall using non-uniform soil convergence mode. Subsequently， through incorporating the layering property of soil ground and introducing the Vlasov foundation model， the differential equation governing the response of adjacent piles induced by foundation pit excavation is established using the two-stage approach， and then its theoretical solution and calculation method are developed based on the finite difference method. Finally， two typical case studies are performed and discussed to verify the reliability of the developed theoretical solution， and the influences of elastic modulus of layered soils and the non-uniform convergence coefficient on the response of adjacent piles are calculated and discussed. The results indicate that the change of soil parameters in the soil layer at the bottom of the foundation pit has the most significant impact on the response of adjacent piles. At the interface of layered ground， the shearing force of adjacent piles has a turning point， while the corresponding foundation reaction shows an abrupt change. With the increase of the non-equal soil convergence coefficient， both the horizontal displacement of adjacent piles and foundation reaction gradually increase at the upper part while decreasing at the lower part. In addition， the influence at the upper part is more remarkable than that at the lower part， while the influence on the shear force and bending moment of adjacent piles show opposite patterns.