Abstract: A low-molecular xylanase (XynA) produced by Streptomyces sp.Z18 was purified and characterized in this study. XynA was purified by 20%-50% ammonium sulfate precipitation and Sephacryl S-300 gel filtration chromatography. The denatured molecular weight of XynA was 22 ku. The optimal temperature and pH value for xylanase activity were 60℃ and 7.0, respectively. The xylanase was stable within pH value 5.0-8.0 and up to 50℃. XynA exhibitedhigh specificity toward different xylans and low or no activity toward other substrates tested. Thehydrolysis of birchwood xylan yielded mainly xylobiose and xylotriose, no xylose was detected by TLC. Therefore, XynA may be suitable for production of xylooligosaccharides.