NOVELTY - Producing xylanase, by preparing nutritive salt solution, preserving Aspergillus niger strain, culturing strain in constant-temperature box, transferring preserved strain to sporogenous culture medium, preparing seed culture medium, culturing A.niger into seed culture medium, centrifuging obtained culture, adding obtained product in culture box for culturing, inoculating the seed culture medium strain into liquid fermentation culture medium, filtering product, extracting xylanase from filtrate, subjecting extract to chromatography and drying product.    USE - The method is useful for producing xylanase.    ADVANTAGE - The method is rapid, simple, easy to perform, economical and environmentally-friendly and suitable for large-scale industrial production.    DETAILED DESCRIPTION - Method for producing xylanase from Aspergillus niger, involves (1) mixing (in g) ammonium sulfate (14), monopotassium phosphate (20), calcium chloride dihydrate (4) and magnesium sulfate (1.5) to obtain nutritive salt solution and placing the solution in refrigerator at 4 degrees C for preservation, (2) preserving A.niger strain by inoculating the A.niger X-1 on inclined plane of test tube containing potato, glucose and agar, culturing the strain in constant-temperature box for 7 days at 30 degrees C and preserving the strain in refrigerator at 4 degrees C below zero, (3) selecting and culturing the A.niger by inoculating the strain in preserving culture medium, transferring the preserved strain to the sporogenous culture medium, transferring the strain from culture medium to constant-temperature culture box at 28 degrees C and culturing for 4-5 days, (4) preparing the A.niger seed culture medium by adding (in g) glucose (30), corn steep liquor (10) and nutritive salt (100) to obtain nutritive solution (1000 ml), (5) inoculating and culturing A.niger by inoculating the strain (2%) on the sporogenous culture medium into the seed culture medium at 30 degrees C, centrifuging the obtained culture at 180 rotation per minutes, adding the obtained product in the constant-temperature vibration culture box and culturing for 3-4 days, (6) preparing the enzyme-producing base culture medium by preparing the liquid fermentation culture medium by adding corncob (2%), ammonium sulfate (1%), potassium dihydrogen phosphate (0.13%), calcium chloride (0.025%), magnesium sulfate heptahydrate (0.05%), ferrous sulfate heptahydrate (0.008%) and zinc sulfate (0.003%), (7) inoculating the seed culture medium strain (25%) into the liquid fermentation culture medium, mixing bran (2%) and yeast extract (1%), regulating pH to 5 at 28 degrees C and adding the mixture in constant-temperature vibration culture box and culturing for 72 hours, (8) separating the obtained product by salting out, centrifuging the fermentation liquid at 4000 rotation per minutes, separating the fermentation liquid, filtering the separated product to obtain supernatant, preferably coarse enzyme liquid, settling the coarse enzyme liquid using saturated ammonium sulfate (20%), adding the ammonium sulfate to the coarse liquid until the saturation degree is 60%, maintaining the mixture at 4 degrees C for 12 hours and obtaining supernatant, and (9) extracting xylanase by gel filtration, subjecting obtained extract to SephadexG-25 (RTM: 2R,3R,4R,5S,6R-6-hydroxymethyloxane-2,3,4,5-tetrol-propane-1,2,3-triol) gel column chromatography and settling obtained product using ammonium sulfate, and subjecting product to SephadexG-100 (RTM: not defined) gel column chromatography of glucan and drying the product to obtain powder.