Abstract: A simplified model for a single pile is established based on the Pasternak foundation and Euler beam models considering the axial second-order effects of pile shaft. The corresponding analytical solutions are derived by utilizing the differential transformation methods and the double-shear theory as well as the pile-soil continuity conditions. Then, considering the dynamic displacement of receiver pile Ⅱ caused by the vibration of source pile Ⅰ, the control equation for horizontal vibration of receiver pile Ⅱ is established, and the analytical solutions for the response of receiver pile Ⅱ are obtained. According to the definition of dynamic interaction factor, the pile-pile horizontal dynamic interaction factor is further obtained. Finally, the superposition principle is used to solve the horizontal dynamic impedance of pile groups, and its rationality is verified by comparing with the existing analytical solutions. On this basis, the influences of soil shear coefficient, pile type, pile to diameter ratio and axial feature parameters on the horizontal impedance of pile groups are discussed through the parametric analysis, and the distribution of the reaction force at the top of the pile and the distribution of the internal force of the pile body are discussed. It may provide theoretical guidance and reference for the design of pile groups in practical engineering.