Abstract: This study aims to optimize the fermentation conditions for the degradation of AFB₁ by Bacillus subtilis Q125 in order to improve its degradation efficiency. On the basis of the single factor experiment, this experiment combined with the response surface method to carry out further experiments on the fermentation conditions that significantly affect the degradation of AFB₁. The results of the experiment indicated that the optimal fermentation conditions were as follows:fermentation time 38.6 h, inoculum amount 5.8%, fermentation temperature 36℃. Through optimizing the fermentation and degradation conditions, the degradation rate of AFB₁ by the fermentation supernatant increased from 69.24% to 100%, suggesting a significant improvement after optimization. Heat treatment 1 (boiled for 15 min) and heat treatment 2 (high temperature and high pressure for 20 min) increased the degradation rate of AFB₁ by 11.18% and 26.63%, respectively (P< 0.05). Proteinase K and SDS treatments reduced the degradation rate of AFB₁ by 5.05% and 36.72%, respectively (P< 0.05). Therefore,It is preliminarily speculate that the active substance of AFB₁ degradation in the supernatant of strain Q125 might be an enzyme(s).