In order to explore the optimal fermentation conditions of cassava for ethanol produc-tion using distiller's yeast,cassava were pretreated by extrusion technology in this paper,and the fermentation conditions including fermentation temperature,solid-liquid ratio,and enzyme concentration,were optimized by the response surface methodology.The results showed that extrusion technology could shorten the ethanol fermentation time,reduce energy consumption,and improve ethanol production efficiency.The optimal fermentation condition was as follows:temperature32 ℃,initial pH 4.5,enzyme dosage 145 U /g,liquid to solid ratio 2.8∶ 1(mL∶ g),distiller's yeast dosage 0.3%,and fermentation time 72 h.Under this condition,the final ethanol concentration from extruded cassava reached11.94 % Vol.