Abstract: Laccase plays an important role in the process of lignin decomposition. The ability of laccase production by Auricularia polytricha 5.584 was high and its activity was stable. In order to further understand the yield of laccase and the degradation of wheat bran by fermentation of this strain, Box-behnken central combination principle was used to design the four-factor three-level response surface test based on single-factor test. The optimal liquid fermentation process parameters were determined by taking the mass concentration of wheat bran, Cu²⁺ mass concentration, initial pH value of the medium, and shaking speed as independent variables and laccase activity as the response. The optimal liquid fermentation process parameters were: the mass concentration of wheat bran 41.50 g/L, Cu²⁺ mass concentration 1.30 g/L, initial pH of medium 5.18, shaking speed 182 r/min. With these parameters, laccase activity reached 188.54 U/mL. The degradation efficiency of wheat bran by the strain was determined, and the degradation rate of lignin from wheat bran reached 68.72% after optimization, which was 1.9 times of that before optimization. To sum up, after the optimization of the liquid fermentation conditions, the activity of laccase and the degradation efficiency of wheat bran by Auricularia polytricha 5.584 were improved, indicating that this strain had a good prospect in the comprehensive application of wheat bran.