Abstract: The finite element and indirect boundary element coupling method is proposed to solve the horizontal vibration of a pile group in transversely isotropic layered soils under scour conditions. The pile group is discretized by a three-node beam element. And then, based on the dynamic solution for transversely isotropic layered soils in frequency domain and considering the pile-pile interactions, the integral equation for the soil is established. After the integral equation is discretized and evaluated numerically, the flexibility matrix of the soil is obtained. The equation for the interaction between the pile group and the soil is deduced using the compatibility conditions between the pile and the soil. After introducing the boundary conditions of the pile head, the solutions for the interaction equation are obtained. Finally, numerical examples are used to validate the proposed theory and results, and to investigate the influence of the scour depth on the horizontal vibration response of the pile group.