Objective In order to obtain robust and reliable ultrasound strain images,this paper presents an improved method of strain estimation from 3D ultrasound images by combining 3D hybrid deformable model and diffeomorphic non-rigid registration.Methods First,we use an anisotropic filtering method to filter out noises,and region growing algorithm based on 2D projection to achieve an initial rough segmentation.Then we apply morphologic closing computation for the more precise results of region growing.In the next step,we achieve accurate cardiac segmentation by deforming the 3D deformable model.We choose the result segmented by the first frame image from 3D echocardiography in a cycle to register other sequence images based on diffeomorphic non-rigid registration method,and subsequently calculate the displacement field and estimate the strain state.Results The experiments show that the proposed method is efficient and accurate.Conclusions The strain analysis of the proposed method is consistent with the property of cardiac anatomy,and is helpful in the diagnosis of cardiac diseases.