Abstract: Based on the volume of fluid (VOF) method and dynamic mesh technology, a three-dimensional fluid sloshing numerical model is developed and solved by considering vapor-liquid two-phase flow, phase change, surface tension, external excitation, and wall heat leakage. The sloshing behavior of a liquid hydrogen tank is systematically investigated under five typical excitation conditions: lateral excitation, longitudinal excitation, uniform acceleration, uniform deceleration, and self-rotation. The main quantitative findings are as follows: under lateral excitation, the liquid center of mass drifted negatively by about 50 mm within 12 s, and the moment of inertia increased from 4.31 kg·m² to 4.48 kg·m²; longitudinal excitation triggered Faraday instability, leading to the formation of standing waves that are amplified over time; in variable-speed conditions, uniform acceleration caused liquid settling toward the tank bottom accompanied by bubble entrainment, with the centroid lifting more than 30 mm along the motion direction, while uniform deceleration induces a forward surge of about 500 mm within 3 s and a peak moment of inertia of approximately 6.1 kg·m²; in self-rotation excitation, centrifugal effects dominated liquid redistribution, forming a bowl-shaped interface with sloshing forces approaching zero. These results reveal the dynamic responses and instability mechanisms of liquid hydrogen sloshing under microgravity, providing technical reference for the structural safety design of cryogenic propulsion systems.