With the development of micro-nano machining technology, the chiral metasurface has been proved to have great application potential in optics. Traditional metal chiral structures are difficult to obtain ideal circular dichroism due to their own ohmic loss, and three-dimensional chiral structures with good circular dichroism but complex structure are difficult to manufacture. The two-dimensional all-dielectric chiral structure of periodic double-Si bricks was adopted. By exciting the non-orthogonal in-plane magnetic dipole moment and electric dipole moment, the optical chiral response could be generated, and the ideal circular dichroism could be obtained. Through simulation optimization, the structure can achieve ultra-high circular dichroism of more than 0.94 at an operating wavelength near 1 550 nm, and can realize the conversion of incident left-circularly polarized light to right-circularly polarized light. This all-dielectric two-dimensional chiral metasurface has the advantages of high circular dichroism, simple structure and low preparation difficulty, and has a wide application prospect in the field of near infrared polarization imaging.