Abstract：To obtain strains for efficient xylose fermentation, a bacteria strain which can convert xylose to ethanol was isolated from decomposed leaves with xylose as sole carbon substrate and was identified as Enterobacter cloacae. The process for converting xylose to ethanol was optimized. The yield of ethanol was 4.95 g/L which accounted for 53.8% of the yield predicted theoretically when Enterobacter cloacae was inoculated at a 6：100 ratio and fermented in microaerophilic condition at 35 ℃ with initial pH 6.5 for 48 h using xylose(20 g/L) as sole carbon substrate. In the presence of a mixture of glucose (10 g/L) and xylose (10 g/L), microaerophilic cultures of the strain produced 4.41 g/L ethanol. The results showed that the strain can effectively co-ferment both glucose and xylose simultaneously to ethanol.