Life Cycle Assessment(LCA), objective of which is to elucidate the impact of biodiesel on energy supply and natural environment and its economic value while giving an assessment on commercialization application of biodiesel, is performed in this study. Based on LCA methodology, production cost and CO₂ emission estimation of rapeseed biodiesel industry were conducted. Results of the assessment indicate that the total amount of absorbed CO₂ during the whole life cycle of rapeseed biodiesel is much larger than that has been emitted and rapeseed biodiesel is really an environment-friendly energy source. With the contribution of biodiesel derived from rapeseed oil made during the process of its full life cycle, green house emissions could be enormously reduced. However, in terms of production cost, the phenomenon that considerable portion of the total cost is occupied by the cost of raw material is observed in rapeseed biodiesel. Specifically, the portion of raw material cost is larger than 89% while the portion of crew oil is larger than 87%. The improvement of economical efficiency in the commercialization application of rapeseed biodiesel depends on the reduction of raw material cost. If we want to develop rapeseed biodiesel in China, government’s encouraging policies, such as tax exceptions and financial subsidies, are necessary.