Abstarct: The eccentrically stiffened cylindrical panels are extremely used in aerospace and mechanics industries. Careful and numerical analysis of eccentrically stiffened panels in the industry is a major step forward in the design of these structures. This thesis presents an analytical approach to investigate the nonlinear buckling analysis of eccentrically stiffened thin FG cylindrical panels with spiral stiffeners on elastic foundations subjected to mechanical, thermal, thermo-mechanical and hygro-thermo-mechanical loads. The panel has the initial geometrical imperfection and the material properties are assumed to be temperature-dependent. The edges of eccentrically stiffened FG cylindrical panel are assumed to be simply supported and the elastic foundation is considered baxsed on Winkler and Pasternak proposed model. Stiffeners are made of full mextal and the present study is baxsed on the Lekhnitsky smeared stiffeners technique. The strain-displacement relations are obtained according to the Von Karman-Donnell geometrical nonlinearity terms and the classical thin shell theory. The nonlinear static problem is solved by applying stress function and Galerkin method. The effects of stiffener's angel, geometrical parameters such as arc length to thickness of panel ratio and arc length to radii of curvature ratio, volume fraction index, initial geometrical imperfection, the stiffness of elastic foundation and moisture concentration on the postbuckling of FG panel for mentioned loadings are investigated. Also effects of temperature gradient through the thickness and effects of different boundary conditions are investigated for thermo-mechanical loading. At the end, suggestions are presented to continue the work.