Thermal effects play significant role in the design of a structure when it is supposed to work in hot environment. For this purpose a thorough analysis of structure is necessary that could precisely consider the effect of temperature change. At first an accurate thermal analysis is required that may be further followed by stress or dynamic analysis. In this work, shell finite element developed by Rolfes et al to perform 3D thermal analysis is studied using Ansys and results are found good when comparing with the 3D solid element result. The interlaminar shear stress analysis of composite plate considering thermal and mechanical loading is studied under different set up of laminate scheme and the results have been found good when compared with the available 3D elasticity results. Then, the effect of thermal stresses on natural frequency of a structure is analyzed considering as thermally prestresssed case under different laminate schemes and boundary conditions. Finaly, A stringer stiffened panel is analyzed under thermal and mechanical load. Interlaminar stresses and natural frequency are evaluated by considering the effect of thermal loading.