The invention relates to the technical field of micro-nano optics, and specifically relates to a planar micro-nano structure capable of producing circular dichroism. The planar micro-nano structure comprises unit structures, wherein each unit structure comprises a rectangular strip and a U-shaped structure, the rectangular strip and the U-shaped structure are in the same plane, the U-shaped structure comprises a first arm, a second arm and a connection bar, the first arm and the second arm are parallel, the first arm and the second arm are respectively connected with two ends of the connectingbar, the rectangular strip is at one side of the U-shaped structure and is parallel to the first arm, and both the rectangular bar and the U-shaped structure are made of precious metal materials. Therectangular strip is arranged at one side of the U-shaped structure, electric charge distribution on the surface of the U-shaped structure is regulated through a coupling role of the rectangular strip and the U-shaped structure, so as to absorb left polarized light and right polarized light differently, therefore, an electric dipole and a magnetic dipole are generated, a specific circulation pattern is formed, and then a large circular dichroism signal is generated.