In this article, a numerical analysis investigates thermal buckling loads of FG rectangular plates with temperature dependent properties. Constituent properties depend not only on thickness direction variable but also on temperature. Therefore calculation of the temperature distribution through the thickness is extremely significant. In this regard, an improved method is introduced for determining temperature distribution. Here, FEM is used to analyze the linear thermal buckling problem based on a higher-order plate theory called CUF. The virtual work principle is used to reach the governing equations for linear thermal buckling analysis. The equations are solved using the SLP method. The effects of some parameters like volume fraction index on the critical temperature differences of FG plates under different heat loads such as uniform, linear, and nonlinear have been examined. The influence of properties’ dependency on temperature is scrutinized too. The results prove the effectiveness of using CUF on critical temperature differences. It is also illustrated that if temperature-dependent properties are utilized in analyzing the thermal buckling loads, the results will be more accurate than using properties without depending on temperature.