Abstract: To take full advantage of the excellent properties of carbon nanotube(CNT),a 3D CNT-based nanostructure was designed theoretically by orderly connecting CNTs with different diameters. It was validated by the first principle that the present nanostructure had stability with a minimum energy of the system. Finally,the Young's moduli and strength of the 3D CNT-based nanostructures under tension and compression were predicted using the molecular dynamics(MD) method. The results show the moduli and strengths of the 3D CNT-based nanostructures can reach 185 ~ 260 GPa and 67 ~ 97 GPa. The 3D CNT-based nanostructures are more stable under compression for the existence of the supporting tube.