In order to improve the biomass of Clostridium butyricum,acetaldehyde addition with an optimized concentration of 0.2 mmol/L at 0 h was first ensured at the anaerobic bottles level,which can significantly increase the biomass,and then,the effects of glucose co-feeding with acetaldehyde strategies on the fermentation characteristics of Clostridium butyricum in a 10 L bioreactor were investigated.The results showed that glucose co-feeding with acetaldehyde enhanced the cell growth(11.37×10~8 CFU/mL),which was 14.5% and 21.1% higher than those of glucose fed-batch culture(9.93×10~8 CFU/mL) and the batch culture(9.39×10~8 CFU/mL).Furthermore,the specific productivity of butyrate and acetic decreased by 18.9% and 17.3%,and the specific productivity of ethanol was increased by 9.7% glucose fed-batch culture,achieving the unity between a higher biomass and a lower acid production simultaneously.The addition of acetaldehyde promoted the NADH oxidation from butyrate biosynthesis pathway to the ethanol biosynthesis branch,which enhanced the ethanol synthesis with the reduced accumulation of butyrate and acetate,and the cell growth efficiency of Clostridium butyricum was improved simultaneously.