This paper addresses the complex component evolution and silicon dynamic deposition characteristics in the traditional Siemens reactor. A two-dimensional heat and mass transfer model coupled with a detailed chemical reaction mechanism was developed. The distributions of temperature, velocity and concentration is presented in detail. The influencing factors (such as feeding mole ratio, inlet velocity, base temperature and reactor pressure) on the molar concentration evolutions of ten major components and silicon growth rate were obtained and analyzed. Results show that base temperature is main influence of HCl mole fraction. In order to get more growth rate of silicon and better silicon quality, the complex operating parameters need to be reasonably designed on collaborative optimization.