Chemical pretreatments significantly improve the enzymatic hydrolysis of lignocellulosic biomass, however, lignin, more or less, left in the residue still presents a significant challenge for the sugar yield. To address this challenge, we proposed a pretreatment strategy using bacteria-assisted (tetrahydrofuran) THF-H2O co-solvent (THCB) to enhance enzymatic hydrolysis under mild conditions. Pandoraea sp. B-6 was proved to effectively remove lignin (to 3.7%) in the corn stover (CS) residue after THF-H2O co-solvent (THC) pretreatment. The compositional and structural analysis confirmed that lignin removal contributed to the expose of more cellulose. The sugar yield varied from 129.6 mg/g to 827.2 mg/g after THCB pretreatment under different conditions, which was increased by 42.6% similar to 2.8% over THC pretreatment (90.8 mg/g similar to 804.5 mg/g) and 1.5 similar to 9.7 times over the untreated CS (84.8 mg/g). Our founding provides a promising technology for lignocellulosic biomass pretreatment in terms of advanced lignin removal, enzymatic digestibility, and reduced energy consumption.