Abstract: It employs a well-to-wheels(WTW) analysis tool,and ascertains bio-butanol-related WTW activities including corn farming,corn transportation,butanol production,butanol transportation,and vehicle operation.According to the 3 kinds of by-product of different methods of distribution,calculation and comparison of the greenhouse gas emissions in the life cycle of corn alcohol.The results show that 1)life cycle GHG emission of the corn butanol reduced 26.0% ~49.5% according to the energy value method and product substitution method;2) bio-acetone that was coproduced with bio-butanol as an alternative to petroleum-based acetone could significantly reduce the life cycle GHG emission of butanol;3) in the life cycle of the corn butanol,the main source of GHG emission was the use of natural gas,diesel and nitrogen,accounting for the total GHG emission by 53.00% ,21.40% and 13.38% respectively.