The Distribution of displacements and STRESSes in a finite length hollow cylinder made of Functionally Graded Material (FGM) subjected to coupled hygrothermal loading was investigated. The simply supported cylinder was under a TRANSIENT coupled hygrothermal loading. Furthermore, the internal pressure and viscoelastic foundation can be considered for the cylinder. The coupled equations of heat and moisture transfer and motion equations of the cylinder were solved employing the Fourier series expansion method, the Differential Quadrature Method (DQM), and the Newmark method along the longitudinal direction, the radial direction, and the time domain, respectively. Finally, the distribution of temperature, humidity, deformations, and STRESSes was obtained. The effects of coupled and uncoupled hygrothermal loading, grading index, hygrothermal boundary condition, and viscoelastic foundation are illustrated in the numerical examples. The results show that the FGM cylinder touches the temperature balance before using the uncoupled model rather than the coupled model. Moreover, by serving the time, the radial displacement, and maximum hoop STRESS increase, and longitudinal displacement decreases to reach steady-state condition.