Abstract: ObjectiveA xylanase-producing thermophilic fungi strain JG-50 isolated from cassava residue was classi-fied and identified, and its fermentation conditions for enzyme production was optimized, in order to provide technical support for its application in agricultural organic waste fermentation utilization. MethodStrain JG-50 was identified based on morphologic observation and sequence homology analysis of D1/D2 domain of 26S rDNA gene. The fermentation conditions including carbon source, nitrogen source, culture time, culture temperature and initial pH were optimized by single factor test, for producing xylanase by strain JG-50. Result26S rDNA sequences similarity was as high as 99%between strain JG-50 and Thermoascus aurantiacus isolate MTCC 4890. Based on morphological observation and data of 26S rDNA sequences alignment, the strain JG-50 was identified as T. aurantiacus. Strain JG-50 was able to produce xy-lanase during solid state fermentation using cassava residue as carbon resource, and the optimal fermentation substrate were, 60% of wheat bran, 0.3% of peptone and 0.2% yeast powder, with pH of 6.0. In the above substrate, the enzyme activity of xylanase reached 4625. 4 U/g after fermenting for 8 days at 50 ℃. ConclusionStrain JG-50 has a consider-able ability of producing xylanase, and shows good application prospect on fermentation utilization of agricultural or-ganic waste.