NOVELTY - A biomass carbon-based catalyst is prepared from circulation waste in furfural production by grinding waste lignocellulosic residue and concentrating waste sugar-containing residue, mixing waste residues, concentrating into paste; carbonizing paste at 180 degrees C for 48 hours to obtain a biomass carbon material; performing deep carbonization of biomass carbon material at 200-500 degrees C for 15 hours under nitrogen protection to obtain biomass carbon-based catalyst material; and impregnating catalyst material into sulfuric acid, then drying and grinding to obtain the biomass carbon-based catalyst.    USE - Method of preparing biomass carbon-based catalyst from recycling waste in furfural production by degrading corncob (claimed).    ADVANTAGE - The method can reduce environmental pollution in crude furfural production process while increasing yield of furfural. The total furfural yield is 14.36%.    DETAILED DESCRIPTION - Preparation of biomass carbon-based catalyst from circulation waste in furfural production comprises:    (A) grinding waste lignocellulosic residue to granularity of 60-80 meshes and concentrating waste sugar-containing residue, mixing the waste residues, uniformly stirring, heating and concentrating into paste;    (B) putting the paste into a carbonization kettle and performing carbonization at 180 degrees C for 48 hours to obtain a biomass carbon material;    (C) putting the biomass carbon material in tubular furnace at 200-500 degrees C, performing deep carbonization for 15 hours under nitrogen protection to obtain biomass carbon-based catalyst material; and    (D) impregnating the catalyst material into 0.5-3 mol/L sulfuric acid at normal temperature for 24 hours, then ultrasonically cleaning for 1 hour, separating by centrifugation, drying and grinding to obtain the biomass carbon-based catalyst.    An INDEPENDENT CLAIM is included for degradation of corncob to produce furfural, comprising adding 5 g corncob and 0.1-1 g biomass carbon-based catalyst into 100 ml water, directly putting mixture into a high pressure reaction kettle for degradation reaction at 170-200 degrees C for 160-200 minutes, then circulating cooling to room temperature, filtering and separating to obtain degradation liquid as furfural.