Abstract: In order to study the characteristics of vehicle water entry at high speed in the fragmented ice environment, such as the evolution of cavitation flow field, vehicle dynamic response and ice breaking load characteristics, a coupled computational model of fluid-structure interaction for high-speed water entry of the vehicle in fragmented ice environment was established based on the Arbitrary Lagrangian-Eulerian method (ALE). The high-speed water entry process of a round-nosed vehicle was investigated through experiments and numerical calculations, validating the effectiveness of the high-speed water entry computational method. By comparing the results of the three-point bending test of the ice material with the numerical results, the reliability of the ice material model used in the calculations was verified. Using the constructed coupled computational model of fluid-structure interaction, the high-speed water entry process of a vehicle in a fragmented ice environment was studied and analyzed. The research focused on the effects of fragmented ice and the gaps between ice fragments on the flow field, dynamic parameters, and loads during the water entry process of the vehicle.The results show that the presence of fragmented ice has an inhibitory effect on the water surface lift and the evolution of splashing after the water entry of the vehicle. In the fragmented ice environment, the impact load on the vehicle during water entry significantly increases, and the process involves greater kinetic energy loss compared to a non-ice environment. However, the duration of the slamming load is consistent with water entry in a non-ice environment. The continuity of the splash crown formed during water entry increases with an increase in the gaps between ice fragments. Within a certain range of ice gaps, the instantaneous slamming load on the vehicle shows a negative correlation with the size of the gap. When the gap is sufficiently large, the variation in the slamming load becomes relatively small.