Abstract: In this study, a large edible fungus, Armillaria mellea, was used as the experimental strain to degrade aflatoxin B₁(AFB₁) by fungal fermentation. Culture temperature, inoculation amount and initial pH were selected as the three critical parameters for single-factor experiments, and the fermentation process was optimized through response surface methodology, utilizing degradation rate as the response indicator. Meanwhile, the degradation effects of the fermentation supernatant, suspension and intracellular fluid of AFB₁ were analyzed, and the degradation mechanism of AFB₁ was explored preliminarily. The effects of proteinase K, sodium dodecyl sulfate (SDS) and heat treatment on the degradation of AFB₁ in the fermentation supernatant were analyzed, and the crude enzyme extracts were obtained by ammonium sulfate precipitation from fermentation supernatants, and the effects of time, pH and metal ions on the degradation of AFB₁ by the crude enzyme extracts were analyzed. The results showed that the highest degradation rate of AFB₁ by Armillaria mellea reached 87.09% could be achieved when the culture temperature was 27 ℃, the inoculation amount was 12.00% and the initial pH was 5.7. The degradation rates of fermentation supernatant, suspension and intracellular fluid were 68.78%, 30.38% and 13.92%, indicating that the fermentation supernatant was the main degradation site. After heat treatment, the degradation rate of AFB₁ was 69.61%, showing no significant difference from the control group, it was inferred that the degradation active component in the fermentation supernatant was mainly the protease which has a certain thermal stability. The crude enzyme extracts exhibited the best degradation of AFB₁ when the pH was 6, with a degradation rate of 67.90%. Mn²⁺ and Cu²⁺ promoted the activity of the crude enzyme extracts, which resulted in respective increments of 4.16% and 6.36% in the AFB₁ degradation rate. This study showed that after process optimization, the fermentation degradation of AFB₁ by Armillaria mellea was effective, providing a new theoretical basis for AFB₁ control.