This study analyzed the causes of thermal deformation during additive manufacturing of a front knuckle structure using the laser powder bed fusion (L-PBF) process. Accordingly, a process simulation model was developed by increasing the layer thickness per scan while reducing the number of layers. Based on the proposed model, a finite element analysis (FEA) was conducted to perform heat transfer and thermo-elasto-plastic analyses. In addition, we propose a simplified process simulation model that incorporates the characteristics of rapid heating and cooling. Using this model, we conduct a thermal deformation analysis without a heat transfer analysis to investigate the deformation behavior. The proposed process simulation models, along with the FEA, effectively analyzed the thermal stress and deformation during the additive process. The results indicated that thermal deformation predominantly occurred in the build direction, with the largest deformation occurring at the edges. Moreover, most additively manufactured structures exhibit residual stress levels approaching the yield stress. Furthermore, the model that omitted the heat transfer analysis significantly reduced the computational time and data storage requirements.