As the oil crisis and environment concerning deepen, the uses of renewable resources have attracted considerable attention. Polyol intended for synthesis of polyurethane polymers was prepared by a novel direct hydroxylation of soybean oil, alternative to petroleum-based process. The transformation can afford soybean oil polyol in excellent yield with a hydroxyl number up to 467.7 mg KOH/g in the presence of OsO4 as catalyst and NMO as oxidant. The major advantages of this approach are: two hydroxyl groups can be readily added to one double bond, replacing conventional two-step methods by an epoxidation step and then a ring opening step; a wide range of hydroxyl numbers can be obtained via varying catalyst loadings; the reaction can be performed at room temperature. The chemical structure of the polyol prepared was further characterized by chemical methods (hydroxyl number and iodine number) and spectra (1H NMR and FTIR spectroscopy), which con?rmed the cleavage of the double bonds and the produce of hydroxyl groups.