Abstract To deeply understand fluid sloshing behavior in non-isothermal fuel storage tanks, a numerical model is built by coupling fluid flow and heat exchange. The external heat leaks and the interfacial phase change are considered. Both the thermal boundary and external sinusoidal excitation are realized by user-defined functions. To capture the movement of liquid-vapor interface during sloshing, the mesh motion treatment is specially adopted with the volume of fluid method coupled. Validated against the experimental results, the standard k-e model is selected to predict fluid sloshing. Based on the numerical model, the influence of sloshing amplitude on hydrodynamic performance is studied. Variations of the vapor and liquid pressure, the sloshing force suffered by the tank and the sloshing moment are investigated. Moreover, to study the dynamic response of the liquid-vapor interface, different monitors are set to measure variations of the interfacial liquid elevation. The results show that the external sloshing excitation has caused great influences on the sloshing hydrodynamic characteristics in liquid oxygen tank. With some valuable conclusions being achieved, the present study is significant to in-depth investigation on the non-isothermal sloshing dynamic process and may supply technique guidance for anti-slosh design on aerospace storage tanks.