Noticeably in casting and heat treatment process, computational methods are commonly engaged to predict process and mechanical characteristics such as solidification time, cooling speed, hardness and residual stress, in which analyzing thermo-mechanical coupled process necessitates such heat transfer, microstructure transformation, and stress. This paper proposes a FDM/FEM hybrid method for thermal stress analysis in casting process; taking advantage of each computational method, we use both FDM and FEM to analyze thermal stress. We use FDM to predict temperature distribution and microstructure and then transfer the result data to FEM to calculate thermal stress distribution. In this process, a systematic field data conversion procedure is developed for a successful data transfer. For the validation of this proposed method, numerical examples are presented and compared with antecedent experiment results. The interface data conversion program developed in this study can be used for any other program as well as FDM and FEM.