Abstract: This paper takes advantge of the anisotropic diffusion for additive noise reducing to reduce the speckle in SAR image. It analyses the distribution of speckle model of SAR image and its Log image, and the result shows that using the anisotropic diffusion for additive noise reducing to reduce the speckle is feasible. Then it gives an algorithm for speckle reducing based on anisotropic diffusion. Numerical results show that the new model has better denoising result than some known methods, and can heep target feature better.