This study proposed a way of reducing the time and memory required for analysis by adjusting the heat input area, to overcome the difficulties in analyzing large-area laser processing. An analytical model was manufactured using existing research results, and based on these results and the volume of the analysis, the efficiency of the new analysis method was verified. The new analysis method proposed in this study can be used as a simple analysis method utilizing a commercial analysis program for diverse areas, including the effect of temperature distribution on the material, the effect of temperature transfer on the mechanical structure, and thermal displacement prediction, in the thermal treatment after processing.