Abstract: With long mission cycles and complicated space missions, modern spacecraft usually need to carry a lot of liquid propellant. Large-amplitude sloshing of liquid propellant in storage tanks will seriously affect the attitude stability and control accuracy of the spacecraft, which is an important problem for the modeling of the spacecraft coupled dynamics system and the accurate control of orbit and attitude. In this paper, a new computational fluid dynamics method for the numerical simulation of large-amplitude liquid sloshing is proposed. The modeling and spatial discretization of the whole gas and liquid mixed fluid system in the tank are carried out by using isogeometric analysis. The pressure-modified fractional step method is used for the time discretization of the governing equations. By decoupling the pressure and velocity variables, the implicit equations are transformed into the explicit equations to improve the computational efficiency. For the common liquid sloshing problem, a simple and efficient mass correction method is proposed to eliminate the liquid mass error caused by the evolution of level set function. Based on the numerical method of isogeometric analysis for liquid sloshing, the coupled dynamics system of liquid-filled spacecraft with solar panels is modeled and the motion of the coupled spacecraft is simulated. The liquid sloshing momentum equation is transformed and introduced into the spacecraft dynamics equations. The numerically stable rigid-liquid coupled dynamics equations of spacecraft affected by liquid sloshing are established. The modeling of solar panels is based on the Kirchhoff-Love plate theory and the vibration of solar panels is solved by modal analysis. By comparing the numerical simulation results with the analytical results, the correctness of the proposed method is proved. Besides, the motion of rigid-liquid-flexible coupled spacecraft is simulated. It is found that liquid sloshing has a significant effect on the amplitude and frequency of spacecraft attitude change and structural vibration.