NOVELTY - Preparation of xylooligosaccharide and lignin using microcrystalline cellulose straw, involves: (1) crushing the agricultural crop straw, water leaching; (2) straw flash explosion depolymerization process; (3) xylanase enzymolysis processing to obtain xylooligosaccharide product; (4) digesting the extracts; (5) obtaining steam from the explosion process in step (4), adding cellulose, enzymolysis, adding laccase, filtering, decoloring, concentrating and drying to obtain microcrystalline cellulose; (6) adding a pH solution, filtering, solid-liquid separation, and drying.    USE - The method is useful for preparing xylooligosaccharide and lignin using microcrystalline cellulose straw (claimed).    ADVANTAGE - The method has mild condition, and avoids the use of toxic reagent.    DETAILED DESCRIPTION - Preparation of xylooligosaccharide and lignin using microcrystalline cellulose straw, involves: (1) crushing the agricultural crop straw to 10-100 meshes, water leaching for 1-6 hours; (2) straw flash explosion depolymerization process of the obtained straw in (1); (3) xylanase enzymolysis processing of product of (2), where the xylan dosage is 2-20000 U/ml, the temperature is 20-60 degrees C, the enzymolysis time is 1-6 hours, the enzymolysis filtration, filter liquid by micro-filter membrane to remove impurity, decoloring, ultra-filtration membrane and nano-filtration membrane separation and desalting, obtaining xylooligosaccharide product; (4) digesting the extracts of (3), and flash explosion depolymerization; (5) obtaining steam from the explosion process in step (4), adding 1-10000 U/ml of cellulose, enzymolysis, temperature is 30-50 degrees C, the enzymolysis time is 1-6 hours, adding 5-3000 U/ml laccase, enzymolysis temperature is 30-50 degrees C, enzymolysis time is 1-6 hours, filter liquid by high pressure, decoloring, concentrating and drying to obtain microcrystalline cellulose; (6) adding a pH solution to the extracts of (5), where the pH solution has a pH of 1-10 at 60-120 degrees C, reacting for 20 minutes to 6 hours, decompression filtering, solid-liquid separation, drying to obtain refined lignin.