The Ms6.9 magnitude earthquake occurred in the Yarlung Tsangpo Grand Canyon region of Minlin City, Tibet Autonomous Region, at 06:34 on November 18, 2017, which led to a number of large-scale landslide debris flows and river blockage in the uninhabited area of the Grand Canyon, resulting in serious hazards. In this paper, we use the 3D spectral element method SPECFEM3D numerical simulation program, combined with remote sensing image data, to simulate and study the ground vibration amplification effect of the complex terrain conditions of the Grand Canyon under the effect of the Ms6.9 magnitude earthquake in Minlin. The results show that: (1) when the seismic wave propagates along the Xixingla rupture, the velocity amplitude amplification occurs in front of the fault rupture, and the uneven energy of the seismic wave and the amplification of the velocity amplitude in many places occur when passing through the high and very high mountainous terrain of the Grand Canyon. (2) The simulated epicenter PGA of the Miling earthquake reached 4m/s2 (0.4g), and the high amplitude area was concentrated near the Xixingla rupture, which was mainly divided into the glacier aggregation area on the north side of the Gyala Peri Peak, the Jiala - Baimagouxiong section of the Yarlung Tsangpo River, the Xixingla - Naiqu section, and the Zhaqu - Duoka section. (3) The PGA of the Yarlung Tsangpo Grand Canyon in the area of rapid topographic change can be 1.97 m/s2, and the amplification rate can be up to 4 times from the bottom to the top of the mountain, and the maximum PGA of 4 m/s2 was detected above the concave and convex body of the seismic source model (4) Three major landslide-intensive zones appeared in the Yarlung Tsangpo Grand Canyon after the Milling earthquake, which were the Jiala-Baimagouxiong section, the Xixingla-Naiqu section, and the Zhaqu-Duoka section, and the PGA high amplitude area coincides with the distribution of landslide-intensive development area. The discussion can be concluded that the Milin earthquake has a non-negligible influence on the occurrence of high watershed-based geohazards in the Grand Canyon area after 2017.