Though experiment of the waste edible oil fuel, life cycle assessment methods of the waste edible oil fuel and diesel fuel were introduced in the process of preparation and combustion. The results showed that the petroleum diesel oil of the blended fuel proportion reduce, contamination index value also reduced except eutrophication potential. The petrochemical diesel oil system is more serious than the biological diesel oil system to the global environment impact, but to compare with the petrochemical fuel oil, it have burned the waste edible oil of the pollutant discharge drops except the NOx.