Laplacian based model editing is one of the most popular shape modification methods for product design. However, most existing Laplacian based methods suffer shape structure and saliency feature distortion, which limits its possible application in shape design of mechanical parts. In this paper, to improve the mesh rigidity and to make the shape deforms physically, finite element method is employed to enhance the Laplacian based model editing, and to keep the saliency features, a robust sharp feature detecting method is further proposed for guiding the modification of the mesh Laplacian in shape deformation. We show how to utilize the enhanced Laplacian for interactive shape design of mechanical parts. The empirical results illustrate that the proposed method yield improved performance compared with conventional methods.