The nonlocal structure tensor of images is defined by using the nonlocal spatial gradients. The eigenvectors of the nonlocal structure tensor consist in a characteristic space for the image,based on which the nonlocal diffusion tensor is constructed. Utilizing the nonlocal diffusion tensor,the nonlocal anisotropic diffusion model for image denoising is introduced. The model differs from the local anisotropic diffusion model in that,not only neighboring pixels but also pixels far away with similar intensities are concerned. The main advantage of taking those pixels far away but with similar intensities into consideration is that the model protects edges and textures much better than the local model.