Abstract: The influence of soil-structure dynamic interaction on structural responses is investigated. The equations of motion are derived under vertical and horizontal earthquake loadings. The seismic responses of high-rising structure are numerically simulated and the results show that the interaction prolongs the period of the structure and increases the deformation. The vertical earthquake increases the response of the structure to some degree. The displacement and the shear forces between floors are larger if the gravity P- effect is considered. A conclusion is drawn that the gravity P- effect should be considered and it will have adverse effect on the whole stabilization on tall buildings on soft soil.