Abstract: Abstract: Corn germ is a kind of byproduct of the wet milling and alcohol industry of corn, which is substantial. Corn germ (dry) contains 35%-56% oil, with linoleic acid (C18:2) being the predominant fatty acid (49%-61.9%). The tocopherol content of corn germ is the highest in all vegetable oils. Corn germ is a cost-effective resource for healthy nutritious oil. In recent years, aqueous enzymatic extraction of corn germ oil has been researched widely. However, this method has the disadvantages of consuming expensive enzyme and long production cycle. In order to reduce the production cost and shorten the extraction time of aqueous method on corn germ oil extraction, the diluted ethanol extraction method was developed in present study based on the consideration that the ethanol added into water was beneficial for demulsifying the emulsion in the homochromous process of oil extraction. Ethanol is a non-toxic and efficient emulsion splitter which has been used in vegetable oil recovery. The product of aqueous ethanol extraction (in appropriate concentration) is directly the free oil rather than the highly emulsified cream after centrifugation. The internal demulsification mechanism is that the diluted aqueous ethanol solution can change the local micro-environment of emulsion and collapse the structure of orderly water molecular around emulsion drops. This method can simplify the follow-up steps and shorten the total production time. Simultaneously, moderate pretreatment was employed to enhance free oil yield further. The research investigated the influence of particle size, solid-liquid ratio, incubation temperature, ethanol concentration, pH value and time for extraction on the oil content of free oil phase, water phase and sediment phase. The result showed that particle size and ethanol concentration made the most contribution to enhancing free oil yield, and extraction time had the minimal impact. The optimal conditions of this aqueous extraction method were: finely ground 4 times (the particle size was 49.18 μm), solid-liquid ratio of 1:7 g/mL, incubation temperature of 70℃, ethanol concentration of 30%, system pH value of 9.0 and incubation time of 2 h. Under the optimal conditions, the free oil yield reached 94.05%±0.32%, the residual oil content in water and sediment phase was 3.49%±0.77% and 2.55%±0.82% respectively. Through determining the quality indices such as acidity, peroxide value and water content of crude corn germ oil extracted by aqueous ethanol solution, it could be concluded that the quality of extracted crude corn germ oil was superior to the national standard of crude corn oil, and similar to the first grade pressed corn oil under the national standard. The crude oil extracted by aqueous ethanol solution only needs a simple refining to reach the demand of intake, instead of the "five-step refining" (degumming, depickling, decoloring, dewatering and deodorizing). It can not only simplify the processing, but also preserve the micro nutrients like phytosterol and tocopherol to the greatest extent. Aqueous ethanol extraction method is an efficient and suitable method of extracting corn germ oil, with the peculiarity of mild conditions, simple operations and superior products. Hence, it can be concluded that aqueous ethanol technology has a good applying prospect in oil production industry.