The mixture of ionic liquid (IL) and aqueous ethanol has been proven to be a promising biomass pretreatment solvent, facilitating the separation of cellulose and faster breakdown of hemicellulose through the disruption of lignin. However, lignin and sugar monomers from the hydrolysis of polysaccharides are soluble in IL and difficult to separate. This complicates the recycling of IL. To address this, CrCl3 and CrCl3 center dot 6H(2)O are used as catalysts for the one-pot conversion of lignin and sugars in the ionic liquid 1-butyl-3-methyl imidazolium chloride ([BMIM]Cl). Furfural resin or humin is produced and separated from IL after the reactions. When catalyzed by CrCl3 center dot 6H(2)O and at a high temperature (>170 degrees C), almost all the lignin and sugars are transformed to humin, which leads to the high efficiency of IL recycling. And the mechanisms of the reactions are studied with guaiacylglycerol-beta-guaiacyl ether (GG) and glucose as model compounds.