Thermal therapy is a promising alternative treatment to conventional surgery for benign disease and cancer. However, it suffers from surface overheating and undesired damage to health tissues. In the present work, we studied the laser-tissue interaction involved in the process of gold nanoparticle (GNP) enhanced photothermal therapy. Monte Carlo method (MC) and Beer's law were applied to calculate the heat generation of tissue and GNPs irradiated by laser. Afterward, the heat generation was used in Comsol as a source term in the bioheat transfer equation. The influence of period heating, GNPs volume fraction, laser irradiation area, and tumor aspect ratio were investigated. It was found that period heating could be used to prevent the surface overheating problem. Despite that higher GNPs volume fraction can lead to higher light absorption efficiency of tumor, lower volume fraction will be better for the heat source distribution. Furthermore, smaller laser irradiation area can be applied to prevent the overheating of the surrounding tissues when the aspect ratio of tumor is larger than a critical value. (C) 2016 Elsevier Ltd. All rights reserved.