Thermomechanical characteristics in the Functionally Graded Materials (FGMs) have been investigated in depth for the precise modeling and analysis of structures in ultimate thermal environments. On this subject, the micro-mechanical interactions of particles in the mixtures of FGMs is necessary to consider the more accurate estimation of structural model. Therefore, the effective material properties are obtained by using homogenization technique based on Mori-Tanaka scheme (MTS) with temperature-dependent material properties. In this regard, present research studies detail temperature-dependent frequencies and thermal buckling behavior of beam model. Then, the physical neutral surface concept is adopted to formulate the decoupled set of stress–strain relations for the FGM models. Also, the First-order Shear Deformation Theory of Beam with rectangular cross-sectional shape including temperature-dependent shear correction factors is developed to improve the practical applications. Furthermore, the results compared with previous data, and the present model is studied in the broad range of temperatures. Specifically, the correlations of shear correction factors and neutral surface shifts are discussed for the models according to temperature and volume fractions. Finally, the thermal stability and the natural frequencies of vibration behaviors are discussed as a result of the mixture ratio for the materials. Furthermore, the mutual interactions of micro-mechanical behavior with the correction factors are especially investigated for thermomechanical analysis.