The invention relates to metamaterial. The metamaterial includes a plurality of concentric rings which have lateral curved surfaces and attach to one another tightly. The bottom radius of each ring is smaller than the top radius. An included angle between a straight line perpendicular to the metamaterial and a connecting line of a radiation source and a point at the bottom of the ring i is theta. The included angle theta only corresponds to a curved surface of the ring I, and the positions on the curved surface only corresponding to the included angle theta are equal in refractive index. The refractive index of each ring decreases with increase of the include angle theta. Jumps of the refractive index of the metamaterial are curved, so that refraction, diffraction and reflection effects of the jumps are reduced greatly. The problems caused by mutual interference are solved, and the metamaterial has better properties.