Abstract: For tetrahedral meshes with non-uniform density,an enhanced 3D ODT(optimal Delaunay triangulation) optimization method for mesh quality is proposed in this paper,which extends the adaptability of ODT.In a tetrahedral mesh,taking an inner node as a core,its vicinity elements form a star structure.Then the core node is transformed into a uniform size space according to size field.The optimal position of the core is obtained by applying the classical ODT optimization method.Finally,the optimal position is transformed into physical space through mean value coordinates.Through the above steps,all inner nodes are optimized and the quality of the tetrahedral mesh is improved.The numerical applications illustrate that the proposed method is effective and robust,and the smoothing result is better than the classical ODT optimization method.