In this paper, we consider a thin simply supported rectangular plate defined as 0 ≤ x ≤ a, 0 ≤ y ≤ b, 0 ≤ z ≤ c and determined the temperature distribution function with heat generation. The thermal stress components σxx, σyy, σxy are evaluated due to thermal bending moments. The results are obtained in the series forms in terms of trigonometric function. Also two special cases for point heat source and moving heat source are considered.