Practice education using virtual medical simulation has been recently introduced to maximize the learning efficiency in clinical environment. Specially, in minimally invasive surgery, the necessity of virtual surgery medical simulation has been substantially increased. Since cauterizing effect occurred frequently in minimally invasive surgery has been represented by simple bleeding, realistic cauterizing effect animation has not been proposed yet. In this paper, we propose realistic real-time cauterizing effect animation. Proposed method changes the individual element of each vertex color of the mesh and uses sigmoid function to impose weights for the smooth color change inside the valid mesh region so that the results of cauterizing effect animation was realistic. In addition, by proposing cauterizing color buffer, overlapped cauterizing effects can be realistically represented. Proposed method greatly improves the sense of the real and absorption in virtual surgery medical simulation so that the education efficiency of doctors and students using medical simulation can be maximized.