Enhancement of Aspergillus niger spore germination and xylanase production induced by heat-shock treatment was studied. The results showed that heat shock treatments at 42 ℃ for 4h,following continuing culture at29 ℃,caused an improvement of spore germination and hyphae growth. Mycelial dry weight( MDW) after heat-shock treatment were higher,especially 38. 5% higher at 24h,than that of constant temperature fermentation during the fermentation process. The maximum biomass by heat-shock treatment was obtained at 72h,12h ahead than that of the control. The total xylanase yield and the yield per unit MDW increased respectively by 46. 2% and 23. 5 at 86h compared with the control. Heat-shock treatment had little effect on the ratio of intracellular xylanase activity to the total activity,and no effect on types of xylanase.