Xylo‐oligosaccharide (XOS) can stimulate the growth of Bifidobacterium, it is widely used in functional food, nutritional products and other aspects. At present, XOS is mainly prepared by hydrolysis of the hemicellulose in plant materials by enzyme catalyzing, resulting the high cost. In order to find an efficient method to reduce the cost, XOS was prepared by synthesis from D‐xylose through oxalate acid catalyzing in this paper, getting the results as following: a light‐yellow product of XOS was obtained with the max yield of 53.75±3.48 %. Its molecular weight is in the range of 459–1306 g/mol, being oligomers contain 3–9 units of D‐xylose units. In addition, the XOS contains both of the basic units of α‐D‐xylose and β‐D‐xylose, mainly connected by both α1‐β4 and β1‐α4 glycosidic bonds. Therefore, this study develops a new method of XOS generation, doing benefit to the high value‐added utilization of xylose.