Fungal pretreatment proposes a promising strategy for the degradation of recalcitrant lignocellulose, which leads to an improvement of lignocellulosic biomass reutilization efficiency in downstream processes. In this study, mushroom cultivation with substrates made of tree trimmings adding with spent brewer`s yeast (SBY) for specific nitrogen loadings obtained higher mushroom yields, which were comparable to those using a commercial substrate, and higher than those reported in literatures using other similar substrates. Cellulase and xylanase activities showed an increased trend in the mushroom cultivation stage. Besides, most lignocellulose was degraded between white spawn initiation and primordia initiation stages. Reduced sugar contents in the substrate via enzymatic hydrolysis were also increased after mushroom cultivation.