In this present book, the behaviors of large amplitude vibration, nonlinear bending and postbuckling of elastically supported nanocomposite beams reinforced by single-walled carbon nanotubes (SWCNTs) in thermal environments with random system properties are studied. The random properties should be modeled as uncorrelated and correlated types. Two types of carbon nanotube-reinforced composite (CNTRC) beams, namely, uniformly distributed (UD) and functionally graded (FG) reinforcements, are considered. The material properties of FG-CNTRCs are assumed to be graded in the beam thickness direction, and are to be estimated through a micromechanical model. The governing random equation are solved using second order perturbation approach (SOPT) and Monte Carlo sampling (MCS). The thermal effects are also included in the motion equations and the material properties of CNTRCs are assumed to be temperature dependent. Numerical studies will be carried out for the second order statistics of nonlinear vibration, nonlinear bending and thermal post buckling of CNTRC beams resting on Pasternak elastic foundations under different thermal environmental conditions.