The aim of this study was to investigate the effect of ⁶⁰Co-γ irradiation sterilization on the quality of Fructus forsythiae. The medicinal powder of Fructus forsythiae was used at different doses. Ingredient concentration,high performance liquid chromatography (HPLC) finger print and antibacterial activity of water extract against Staphylococcus aureus were used before and after irradiation for comparison. A near-infrared spectrum (NIR) consistency model of Fructus forsythiae was established by near-infrared spectroscopic methodology and the optimum dose of ⁶⁰Co-γ irradiation was investigated. The results showed that there was very significant difference (p<0.01) in the contents of the two compounds (forsythiaside A and forsythiaside I) compared to unirradiated samples. The similarity of HPLC fingerprints was decreased. The water extract's effectiveness against Staphylococcus aureus before and after irradiation in each sample showed no significant difference (p>0.05). The NIR consistency evaluation model was established to determine the irradiated samples. The microbial populations could be reduced to a lower degree at 5 kGy absorbed dose irradiation. ⁶⁰Co-γ irradiation sterilization would affect the quality of Fructus forsythiaeat 10 kGy dose. It is recommended that the irradiation sterilization dose not exceed 5 kGy.