In this paper, a simplified analytical method is developed for the axial harmonic response of totally and partially embedded pile groups in homogeneous and layered soil deposits. Based on BDWF model, finite element sub-structure method is used to setup the dynamic model of cap-pile groups which can precisely simulate kinetic interaction and inertial interaction. A comprehensive parameter study focuses on the influence of caps’ elastic modulus and mass density on pile groups’ dynamic response, and then points out the limition of rigid cap in practical design. An approximate solution is finally presented for the internal forces distributed on pile heads due to pile-to-pile interaction. The solution of above approach was compared with that of traditional simplified model (rigid and massless cap solution) in simulating an in-site experiment and dynamics response of partially embedded pile groups for offshore wind farm.