Photo-thermal response is one of the basis processes of laser irradiated tissue, dominating the laser surgical process and depending on the effect of laser treatment. To better investigate the interaction between ablative laser and skin, and more understand the light distribution and temperature distribution during the laser irradiation. Numerical simulation, which based on finite elements method (FEM), was used to solve the bio-heat and the thermal damage equations. Laser parameters can be adjustable during the process of surgery. Optical transmission, scattering coefficient and absorption coefficient in bio-tissue under laser irradiation were carried out to analyze the thermal response, which resulted from the absorbed light energy. And then, optical coherence tomography (OCT) was applied to study the injure in mice skin. The result is consistent to Numerical simulation, which will help to improve the laser therapy.