The invention relates to an optical device, in particular to an optical polarizer capable of dynamically adjusting an AT (asymmetric transmission) signal and a using method of the optical polarizer. The optical polarizer comprises a single-layer chiral structure formed by arranging a plurality of periodic units with the same structure in rectangular periodic arrays, wherein each metallic nanostructure unit comprises a metallic nanorod and an S-shaped metallic nanostructure, the metallic nanorod is formed by connecting a first constituent block and a second constituent block, the first constituent block is made of metallic magnesium, and the second constituent block and the S-shaped metallic nanostructure are made of precious metal. According to the structure, the size and position of the AT mode can be adjusted by adjusting the relative effective length of the metallic nanorods through dehydrogenation and hydrogen absorption, and the structure can be integrally formed; during use, theAT signal of the structure can be adjusted only by hydrogen absorption or dehydrogenation as required; preparation and use methods are simple and convenient, and operation is easy.