The circular dichroism spectral sensing effect of a chiral double-layer plasmon metasurface is investigated theoretically. By analyzing the spatial distribution of the electromagnetic field in the structure, it can be found that the enhanced chiral resonance response of the artificial structure is due to the local plasmon resonance in the slit and the coupling effect between two metasurfaces, and the circular dichroism transmission spectrum and co-polarized transmission spectrum of this structure respond differently to the refractive index changes of the biochemical layer. Under proper structural parameters, the sensitivity of circular co-polarized spectrum and circular dichroism spectrum can reach 109 nm/RIU and 111 nm/RIU, respectively. It is shown that the artificial chiral structure has the functions of co-polarized spectrum and circular dichroism spectrum sensing, and has potential application value in the field of new biochemical sensor devices.