The invention discloses a CuO composite mesogen catalyst modified by an atomic-level auxiliary agent, which comprises a main catalyst CuO mesogen and a single-atom auxiliary agent M1 or a double-monoatom auxiliary agent M1 and M2, and M1 and M2 are dispersed by single atoms The state exists, wherein, the M1 is selected from any one of Zn, Zr, Ti, Mn, Fe, Co, Ni, Sn, In, Ce, Ru, Pd, Au, Pt, Rh, and the M2 is selected from Any one of Ni, Au, Pt or Pd. The CuO composite mesogenic catalyst modified by the atomic-level auxiliary agent of the present invention has excellent catalytic performance, is used for the hydrochlorination reaction of silicon powder and HCl as raw materials, and can realize the selectivity to trichlorosilane and silicon tetrachloride Synthesis is regulated, while reaction temperature and energy consumption are reduced, and product yield and silicon powder conversion rate are increased.