Abstract: Non-thermal plasma in atmospheric pressure was explored for the preparation of polysilicon from SiCl4. Two ac power supply sources of a positive pulse with frequencies of 8 and 100 kHz, respectively, were compared for polysilicon preparation. The samples prepared by using the 100 kHz power source were crystalline silicon. The effects of H2 and SiCl4 volume fractions were investigated. The optical emission spectra showed that silicon species played an important role in polysilicon deposition.