Abstract: To accurately reveal pile-soil dynamic interaction and remedy the shortcoming of dynamic Winkler foundation-Bernoulli-Euler beam model (E-W model), this paper considers soil shear effect and pile shear deformation, and establishes a dynamic Pasternak foundation-Timoshenko beam model (T-P model) to simulate pile-soil dynamic interaction. And the analytical solution for horizontal vibration of the active pile under horizontal dynamic and vertical load is derived. Based on this, the governing equations for horizontal vibration of the passive pile are established by the principle of pile-pile dynamic interaction. A transfer matrix method is used to consider the layered characteristics of soil, and an initial parameter method is utilized to calculate the pile-pile dynamic interaction factors. The correctness of the proposed method is validated by comparing the calculated results with existing solutions. Through the analysis of parameters, it is concluded that the shear effect of soil can enhance horizontal dynamic interaction factors. Given the parameters of pile and soil, there exists an "effective pile length" (L_d=10d~15d) for active and passive piles. When the length-diameter ratio of the pile is in the range of L/d=5~10, the influence of pile shear deformation on dynamic interaction factors should not be ignored. In addition, the vertical load has the most significant effect on cross-swaying-rocking dynamic interaction factor.