Abstract: The bleeding simulation in the available virtual surgery system cannot well satisfy the unique biological features of blood. In order to improve the authenticity of bleeding simulation, an improved SPH method is developed for bleeding simulation in this work. The improved WCSPH is used to improve the solution of pressure in traditional algorithm, making it more suitable for the unique features of blood. Furthermore, an adaptive smoothing length algorithm based on density is proposed. The algorithm enables the particle system to adaptively adjust the smoothing length according to the density of the neighbor particles, which increases the interpolation accuracy, reduces the computing error, and enhances the system stability. The experimental results show that this method improves the visual effects of edge, increases the stability of particle system alongside a relatively high computational efficiency. Moreover, it can ensure the authenticity of the simulation effects and improve the real-time capability of simulation.