Owed to wide use of pulsed lasers in a medical field, a deep understanding of their effects on the temperature increase in tissue and the subsequent tissue thermal damage in a coagulation process may be a matter of importance. The influence of laser beam profile, repetition rate and pulse width on temperature distribution and the subsequent thermal damage in tissue are studied using finite element method, which solves the axis-symmetry bio-heat equation in tissue subjected to far IR pulse laser irradiation. Some conclusions are obtained: as energy/pulse remains constant, Gaussian laser beam profile rather than a top-hat beam will increase the in-depth tissue thermal damage at and near the center of the spot region, increasing in repetition rate will increase the temperature distribution and subsequent damage zone. As pulse width decrease, high temperature may be reached leading to cause a quantitatively and qualitatively damage which can be recognize as an increase in the size of the damage zone and a higher value of thermal dose. An increase in pulse width will reduce the rate at which energy deposed in the tissue which result in low extent of temperature increase which result in reduction of the damage zone quantitatively and qualitatively
