In order to meet the needs of 3D seismic image filtering, the method of 3D anisotropic diffusion filtering has been studied. And the relationship between the eigenvalues of structure tensor and the stratum structure has been analyzed in detail. By using structure tensor, extracted the local structure of 3D seismic image, and using the improved coherent enhancement diffusion method, designed eigenvalues of diffusion tensor, and constructed the diffusion tensor to control the diffusion rate of three main orientation. And anisotropic diffusion filter algorithm and program has been designed. The results of 3D theory model test and real seismic data processing has verified the correctness and effectiveness of this method. And the filtering results demonstrate its efficiency to remove incoherent noise as well as to enhance the continuity of seismic events and geologic sediments. This diffusion filter can improve the quality of seismic data wholly.