为探究立式圆柱液舱内自由表面三维共振晃荡特性，采用模型试验与光滑粒子流体动力学（SPH）相结合的方法开展研究。通过试验数据验证了SPH数值模型的准确性，结合试验和数模探究了自由表面在不同外部激励参数下对舱壁的冲击压力特性。研究结果表明：自由表面模态受激励频率与幅值共同作用，随激励幅值增大，混沌旋转波与稳定旋转波模态的频域响应范围扩展；舱壁所受冲击压力与外部激励幅值呈非线性正相关；相比于平面波模态，自由表面旋转运动会对舱壁产生更显著的冲击压力，其中混沌旋转波模态的压力时程曲线无法达到稳态响应，其冲击压力强于稳定旋转波模态。研究结果可为海洋工程立式圆柱液舱设计提供晃荡载荷评估依据。

To investigate the three-dimensional resonant sloshing characteristics of free surface in a vertical cylindrical tank, a combined approach employing model experiments and smoothed particle hydrodynamics (SPH) was adopted. The accuracy of the SPH numerical model was validated through experimental data, and both experimental and numerical methods were employed to examine the impact pressure characteristics on tank walls under different external excitation parameters. Results indicate that the modal responses of the free surface are governed by both excitation frequency and amplitude. Increasing the excitation amplitude significantly expands the frequency response ranges of chaotic rotational waves and stable rotational waves. The impact pressure exhibits a nonlinear positive correlation with the excitation amplitude. Compared to planar wave modes, rotational motions (particularly chaotic rotational waves) generate substantially higher transient impact loads on the tank walls. Notably, the pressure time-history curves of chaotic rotational waves fail to reach steady-state responses and demonstrate stronger impact pressures than stable rotational waves. These findings provide critical insights for evaluating sloshing-induced loads in the design of marine vertical cylindrical liquid tanks.