Hydrazine hydrate and organosolv synergetic pretreatment of corn stover was developed. With the aid of alkaline and reductive hydrazine hydrate, a high delignification rate (77.94%) and total sugar yield of 90.27% (96.60% glucose, 78.82% xylose) based on the pulp could be obtained using hydrazine hydrate (10 mmol/g corn stover) and aqueous ethanol (60 vt%) as the solvent system. Analysis techniques such as FT-IR, SEM, XRD, and NMR were employed to characterize the structure and property changes of stock before and after pretreatment to evaluate the effect of hydrazine hydrate. A mechanism is proposed for the presented system.