In this paper， the horizontal vibration of partially embedded piles in unsaturated soil is mainly studied. In order to simulate the real service state of high bearing platform piles of bridge pile foundation， considering the combined action of horizontal harmonic load and vertical static load， the coupled vibration theoretical model of unsaturated soil and partially embedded piles is established by using Timoshenko beam model and three dimensional continuum model. The analytical solution of horizontal dynamic response of pile is obtained by the decomposition technique of potential technique and the transfer matrix method. The rationality of the solution is verified by comparing the proposed solution with the results of previous scholars. Based on the established theoretical model， the influence of vertical load， embedding ratio and saturation on the horizontal dynamic characteristics of partially embedded piles are discussed in detail. The results show that： the stiffness factor decreases rapidly with the increasement of vertical load，but the damping factor decreases slightly at the time； Both stiffness factor and damping factor decrease with the increase of embedding ratio； The horizontal displacement， rotation angle， bending moment and shear amplitude of the pile increase with the increasement of the embedding ratio， and the amplitude position moves upward gradually； When the saturation is greater than 0.9， the stiffness factor increases rapidly with the increase of saturation， and the damping factor basically remains unchanged.