Abstract A new integrated process is proposed to convert whole plant cassava to bioethanol. It could improve the utilization of straw and contribute to the industrial production of cellulose ethanol. The key technologies were the by-products organic acids enhanced pretreatment of straw, and the mixed liquefaction and fermentation of cassava root starch and cassava straw sugar. Process simulation technology and life cycle assessment were employed to simulate and analyze the bioethanol processes from the cassava root, cassava straw and whole plant cassava, respectively. The results showed that cassava root ethanol had the lowest process energy consumption as 4186 MJ/1000L ethanol. Cassava straw bioethanol had a negative net energy value as −1329 MJ/1000L ethanol. The whole plant cassava bioethanol showed a competitive net energy ratio = 1.45, the highest reproducibility = 2.35–2.55, and the lowest environmental emissions. The effects of fermentation efficiency and straw utilization rate on the integrated process were further investigated, which would help the practical application of the integrated process. When the fermentation efficiency was maintained at more than 80%, the straw utilization rate was more conducive to improving the renewability and environmental friendliness of bioethanol. Moreover, the influence of the process simulation deviation on life cycle assessment was determined by Monte Carlo Analysis. The net energy analysis and environmental impact assessment proved that the proposed integrated process was beneficial for energy utilization and cleaner production.