This paper presents the effect of material-temperature dependent on the vibrational characteristics of a functionally graded (FG) thick beam by using finite element method. The beam is modeled by higher order shear deformation theory (HOBT), which is accommodated for a thick beam. The material properties are proposed to be temperature-dependent and vary continuously through the thickness direction according to a power-law distribution. The equation of motion is derived by using Lagrange’s equations. The finite element method is exploited to discretize the model and obtain a numerical solution of the equation of motion. The model is verified and compared with previously published works. The effects of material distributions and slenderness ratios on the fundamental frequencies and mode shapes are presented. Also, the effects of material-temperature dependency on the fundamental frequencies are figure out. Results show that the former mentioned effects play a very important role on the dynamic behavior of thick FG beams.