Production of polysilicon by chemical vapor deposition of SiHCl3 with a fluidized bed reactor is a competitive technology. As equilibrium conversion can be approached in a fluidized bed reactor, a reliable thermodynamic analysis is very important. However, inconsistent thermodynamic analysis results have been reported in the literature. The present work studied the effects of thermodynamic data and species selection, and recommended that JANAF was the best C-p data source and the minimum set of species included the following eight species: H-2, HCl, SiCl4, SiCl2, SiHCl3, SiH2Cl2, SiH3Cl and Si. Then, the influence of operating conditions on the equilibrium was studied. For the SiHCl3-H-2 system, both the yield of silicon and selectivity to silicon reached their maximum at (up to 1100 degrees C), and low pressure and high H-2 feed ratio were of benefit for silicon production. For the SiHCl3-SiCl4-H-2 system, silicon could be produced only at 900-1400 degrees C, and reducing pressure and increasing H-2 feed ratio enhanced the yield of silicon. Meanwhile, the operation map for zero net by-production of SiCl4 by directly recycling the produced SiCl4 was determined. (C) 2015 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.