In this paper, the degradation rate, energy yield and the degradation by-products of SF6 was studied when different concentrations of NH3 were added. When NH3 concentration increased from 0 to 2%, the degradation rate efficiency(DRE) of SF6 increased from 60% to 97.23% under the flow rate of 50ml/min and 94W input power. The energy yield(EY) reached 4.16g/kWh. In addition, we found that increasing the flow rate to 250ml/min, the DRE decreased to 58.71%, but the EY increased to 12.55g/kWh. The main gas by-products are SOF2, SO2F2, SO2, OF2, HF and NF3. When the concentration of initial NH3 increased, the SO2 concentration increased while the concentrations of SOF2, SO2F2, SOF4 decreased. In addition, we found that a pale yellow film formed on the surface of the reactor wall. XPS analysis showed that the solid products were mainly S, NH3HF and NH4HF2. The emission spectra show that NH3 addition can effectively promote the formation of active particles and increase plasma density.The addition of NH3 can convert some of the sulfur and fluorine into solid products and reduce the production of toxic gases.