A cDNA sub-library from the fungus Trichoderma reesei grown on xylan was constructed in S.cerevisiae recombinant strain H475 harboring a xylose reductase (XR) gene from Pichia stipitis. The xylitol dehydrogenase (XDH) gene was screened from sub-library on a SC selective medium in which xylose was used as a sole carbon source. The length of XDH gene, xdh1, was about 1.3 kb. Southern, Northern and Western blots were carried out, indicating that xdh1 has high affinity with T.reesei and the molecular weight of the xylitol dehydrogenase from T.reesei was about 40 kDa. The strain HX1 harboring both the XR gene from P.stipitis and the XDH gene from T.reesei was able to grow on the xylose medium and converted more than 90% of the xylose into xylitol, ethanol, and other by-products.