Current studies on the failure modes and safety evaluation of asphalt concrete core walls and dam bodies under the spatial oblique incidence of seismic waves are significantly lacking. This paper considers the spatial variability of the SH wave incident azi? muth， and constructs the non-uniform free field on the foundation boundary based on the wave field superposition principle. It estab? lishes a wave input method for SH waves with three-dimensional space oblique incidence. An empirical formula is then established for the change in the instantaneous tensile strength of asphalt concrete with the strain rate， based on the test results. A new method for core wall safety evaluation， based on instantaneous tensile stress and instantaneous tensile strength， is proposed to judge the tensile failure of elements. The influence of the incident azimuth on the dislocation between the transition material and the core wall， and the stress of the core wall， are analyzed. A shear failure evaluation of the dam body is carried out， and the seismic weak parts of the core wall and the dam body under different incident orientations are clarified. The results show that the seismic wave vi? bration direction parallel to the water flow direction is the most unfavorable excitation direction for transition material dislocation， core wall tensile stress， and local dynamic shear failure of the dam body. Compared with the vibration direction parallel to the dam axis direction， the horizontal detachment and vertical dislocation of the transition material increased by 19.25 times and 2.19 times respectively when the vibration direction was parallel to the water flow direction. The maximum tensile stress of the core wall in? creased by 1.8 times， and the dynamic shear failure depth of the upstream dam slope element deepened. Moreover， compared with the core tensile failure judgment method proposed in this paper， the traditional judgment method will lead to an overestimation of the damage degree of the core wall.