Abstract: Based on the principle of Gibbs free energy minimization，the thermodynamic analysis on the chemical reaction system of the co-hydrogenation of silicon tetrachloride and silicon was carried out.Through the analysis on the composition distribution of chemical equilibrium products，the main products of the reaction system were confirmed as HSiCl₃（TCS）， H₂SiCl₂（DCS）， and HCl，and three independent reactions were constructed at the same time.The relations of heat of reaction（ΔrHθm），free energy（ΔrGθm），and equilibrium constant（Kθp）versus temperature were discussed.The calculation was made under the conditions of temperature at 673~923 K，pressure range at 101.325~2 026.5 kPa，and raw material amount-of-substance ratio（H₂/SiCl₄） at 1~5.Results showed the equilibrium conversions of SiCl₄ and SiHCl₃ yield reduced with the increasing temperature of reactions of producing TCS and DCS；high pressure and proper raw material mix ratio（amount-of- substance ratio of H₂ to SiCl₄） were favorable for the enhancement of SiCl₄ conversions and SiHCl₃ yield.

Key words: SiCl₄, SiHCl₃, chemical reaction equilibrium, thermodynamics