Abstract: In order to address the biological resistance of lignin during biomass refining, this study selected a lignin-degrading fungal that was used for the distillers' grains pretreatment. Fourier infrared spectrometer, X-ray diffractometer, scanning electron microscopy, Zeta potential and nanoparticle size analyzer, low-field nuclear magnetic resonance analyzer, and thermogravimetric analyzer were used to characterize the microstructure and physicochemical properties of distillers' grains before and after preconditioning. The results showed that this lignin-degrading strain was the genus Trametes, named Trametes sp. SCU31(T. sp. SCU31). T. sp. SCU31 was able to efficiently degrade lignin in distillers' grains, which could degrade acid insoluble lignin and acid soluble lignin by 33.86% and 50.88%, respectively. The surface of distillers' grains pretreated by T. sp. SCU31 was covered with holes and fragments, resulting in the exposure of more fiber bundles and a significant increase in the accessibility of cellulase. These results indicated that the T. sp. SCU31 pretreatment efficiently degraded lignin and disrupted lignocellulosic resistance.