Wheat bran is a natural and renewable agricultural by-product. Among them, xylan is the main component of non-starch polysaccharides in wheat bran and has excellent physicochemical properties and physiological activities. Wheat bran is mostly used as a raw material for other cheap products such as vinegar, soy sauce or feed, resulting in a waste of resources. Xylan was prepared by different gradient concentrations of ethanol from wheat bran high-temperature cooking liquor and four precipitation fractions were obtained, which were EXy40, EXy60, EXy80 and EXy90. Monosaccharide compositions, relative molecular weight and infrared spectrum of four kinds of xylan were determined. Moreover, effects of enzymatic modification on the in vitro antioxidant activities of xylans were investigated. As a result, the relative molecular weight distribution of the four xylan components was narrow and the polydispersion coefficient was small. The in vitro antioxidant activities of the four xylan components were significantly enhanced after enzymatic hydrolysis. The scavenging effect on hydroxyl radical was improved, and the removal rate of EXy40, EXy80 and EXy90 could reach more than 97%. This study might provide a certain theoretical basis for the comprehensive development and utilization of wheat bran and the in-depth study of the structure-activity relationship of xylan extracted from wheat bran.