Laser induced thermal therapy (LITT) emerged in recent years as a minimal invasive treatment method for otherwise oftentimes inoperable brain tumors, such as glioblastomas. During the thermal ablation process, the procedure carries the risk of destroying healthy brain tissue adjacent to the tumor. Limitations in the spatial distribution of the real-time monitoring MR thermography system currently allow only a rough representation of the damage zone during surgery. For this reason, improved pre-operative simulations of tissue heating and the resulting tissue damage could be valuable to optimize clinical treatment protocols while minimizing the risks of the procedure. In this study a method is presented, to simulate the ablation process of the LITT with the finite elements method (FEM) using the simulation software COMSOL MULTIPHYSICS. Thereby the temperature distribution is displayed and, based on this, the extent of the tissue damage during the process is simulated. Therefore, relevant parameters for the ablation process, such as optical and thermal properties, blood per-fusion, and the interface between healthy and tumor tissue were investigated and their influence on temperature distribution and extent of tissue damage was described.