Taking the water tank of ordinary railway passenger vehicle as the research object,in the process of train acceleration and deceleration,the liquid sloshing problem in the water tank was modeled and numerically analyzed using a two-way fluid-solid interaction method. By studying the gas-liquid two-phase flow distribution state in the water tank,the stress time history diagram and displacement history diagram of the water tank are obtained,and a more accurate analysis of the structural strength of water tank is achieved. By comparing with a water tank without wavebreakers,the cushioning effect of the wavebreakers in sloshing is further clarified,which provides practical and reliable analysis method for the design of tank structure of railway passenger vehicle.