Three dimensional (3D) metamaterials are periodic artificial microstructures arranged in three-dimensional space. They are in scale of subwavelength, thus getting extraordinary physical properties which are not found in nature. The recent developments on basic theory and manufacturing process of the 3D metamaterials are discussed in this letter. Manufacturing processes of the 3D metamaterials are sorted out, including printing circuit board and assembly, machining technology, 3D printing technology, micro/nano-manufacturing technology. As the representative devices of 3D metamaterials, the electromagnetic cloaks, lens antennas, absorbers and flexible metamaterials are discussed to show how the 3D metamaterials control the electromagnetic-wave. Devices of left-handed metamaterials, graded refractive index metamaterials, intelligent metamaterials are also discussed. Finally, the development trends of 3D metamaterials in future are discussed and predicted according to the present problems of 3D metamaterials.