Bacillus TSH1 (B.TSH1) is a new isolated butanol-producing microorganism in our laboratory.B.TSH1 can grow and ferment under facultative anaerobic condition, while it share similar fermentation products and phase with Clostridium acetobutylicum.To illustrate the relationship between the product and the enzymes activity in B.TSH1, the key enzymes of butanol and ethanol-forming were assayed, including of butyraldehyde dehydrogenase, butanol dehydrogenase and alcohol dehydrogenase.The results showed that the activity of all the three enzymes increased rapidly after the initiation of fermentation and then decreased.All of the enzyme activity peaked before 21h, when the product concentration were still low and began to increase promptly.The activity of alcohol dehydrogenase reached maximum of 53.62 U/mg at 12 h;and the enzyme activity of butyraldehyde dehydrogenase and butonal dehydrogenase reached maximum of 9.95 U/mg at 21 h and 15.62 U/mg at 15 h, respectively.The enzyme activity then declined and maintained low level after 24 h,while the concentration of butonal, acetone, and ethanol kept increase until the end of fermentation.