Abstract: In this paper, the chaotic dynamics of liquid-filledflexible spacecraft is investigated in the large angle attitude maneuverfrom minor axis to major axis with the influence of viscous damping ofliquid fuel and the torsional vibration of flexible appendage. In addition,the coupled influence is focused in this paper. The dynamic equations arederived and transformed into a perturbation form. Melnikov's integral methodis used to predict the chaotic attitude of the spacecraft, compared with thenumerical results of the system. Furthermore, the effects on chaoticattitude of the spacecraft are investigated of spacecraft shape, theinertial momentum and the damping properties of liquid fuel, and thefrequency of flexible appendage.