Abstract: The antiknock security of high dams with large reservoirs is an important research topic of national defense security. Aiming at the stability and safety evaluation of gravity concrete dams subjected to underwater explosion shock, the propagation of far-field underwater explosion shock wave and its interaction with the dam are studied. Based on the wave theory and plane wave hypothesis, a theoretical calculation model for the explosive dynamic stress field of gravity dams is established. Then, a simplified time-history analysis method is proposed for the dynamic stability of gravity dams under far-field underwater explosion shock wave. Finally, the dynamic stability of a gravity concrete dam with the proposed method is analyzed. The results show that: the stability safety factor of the gravity dam increases firstly, then decreases, and finally increases to a constant under impact loading; the combined action of tensile wave and shear wave, reflected by the downstream dam surface, is the main reason for the reduction of foundation surface stability safety factor.