Abstract: A hemicellulose degrading bacteria was isolated with rotting wood as a source.Hydrolysis spot diameter measurement of hemicellulose plate and extracellular enzyme activity was used.The strain J-25 was identified as Cellulomonas by 16 S r DNA sequencing analysis, named Cellulomonas sp. J-25. And characteristics of enzyme production and enzymatic properties were studied.The results indicated that fermentation conditions for enzyme production of strain J-25 was: temperature 30 ℃, the initial p H of 7.0, bran concentration of 20 g/L, yeast powder concentration of 10 g/L, liquid volume of 50 m L ( 250 m L flask) , hemicellulose activity may reach 62.8 U/m L. The optimum enzyme reaction conditions were as follows: p H6.5, temperature of40 ℃, substrate concentration of 15 g/m L, the reaction time of 30 min. These will provide experimental evidence for hemicellulose biodegradation.