Regarding the dynamic analysis and seismic safety of high gravel soil core rockfill dams, this paper systematically investigates the dynamic response characteristics of the dam-foundation system under strong earthquakes using the three-dimensional nonlinear finite element time-history analysis method. Based on an equivalent viscoelastic constitutive model to characterize the nonlinear dynamic properties of the gravel soil core, the site-specific response spectrum determined by the scenario earthquake method is used as input through artificially generated seismic waves. Under both the design earthquake (OBE) and check earthquake (SEE) conditions, the spatial distribution of acceleration response and its amplification effect along the dam height, the maximum dynamic displacement and seismic permanent deformation of the dam body, the shear safety of the core wall, the liquefaction resistance safety of the upstream filter material, and the seismic stability of the dam slopes are the studied. And the key findings under the OBE condition are as follow: ① The maximum acceleration amplification factors were 3.63 in the dam-axial direction, 3.72 in the streamwise direction, and 3.76 in the vertical direction, acceleration response was strongest in the streamwise direction, exhibiting a significant whipping effect. ② The maximum dynamic displacements were 14.0 cm (dam-axial), 14.8 cm (stream direction), and 6.5 cm (vertical), larger dynamic displacements were primarily concentrated in a localized area near the dam crest at the central valley section. ③ The internal shear safety factors of the core wall were all greater than 1.0, and the core wall will not experience shear failure. ④ The permanent axial deformation of dam is manifested as the squeezing deformation from both banks towards the riverbed. The longitudinal deformation of the upstream dam shell points upstream along the river, while that of the core wall and the downstream dam shell points downstream. The maximum settlement of the dam is 35.6 cm, occurring in the upstream dam shell near the dam crest, with the maximum settlement amounting to 0.27% of the dam height. ⑤ The maximum pore pressure ratio of the upstream filter I is 0.72, which is less than 1.0 and will not trigger seismic liquefaction. ⑥ The finite element dynamic time-history stability analysis shows that the safety factors of the upstream and downstream dam slopes are both greater than 1.0, and there will be no slope instability failure.