The invention discloses a modulation method and product of a terahertz metamaterial and belongs to the field of metamaterials. The method comprises the steps that firstly, a periodic cylindrical air cavity is formed in a substrate of a PDMS material, then a flexible medium PDMS thin film is arranged above the air cavity, and the metamaterial is arranged on the PDMS thin film; then, outside pressure is added, so that the flexible medium PDMS thin film above the air cavity is protruding or sunken, then geometric parameters of the metamaterial on the PDMS thin film are changed, and finally the response to the incident terahertz wave is modulated. The invention further provides the product which achieves the modulation method. The product comprises a metamaterial structure and a PDMS substrate, the metamaterial structure is arranged on the PDMS substrate, the metamaterial comprises the PDMS thin film and a two-dimension periodic array which is arranged on the PDMS thin film, and the periodic cylindrical air cavity is formed in the PDMS substrate. The modulation method is simple and reliable, is easily controlled, and is relatively high in modulation performance of the linearly polarized beam and the circularly polarized light.