Abstract: A simple and convenient method on xylo-oligosaccharide product (XOS) quantitative determination was established based on dilute sulfuric acid hydrolysis combined with high performance liquid chromatography (SAH-HPLC) detection. The protocol is as following:on HPLC system, the xylose content of XOS, the standard xylose and its hydrolysates was determined, and then total XOS content was calculated according to its xylose content changes, the xylose decomposition ratio and the conversion ratio of XOS to xylose during SAH. The optimum conditions for SAH step is at 6.0% sulfuric acid content and 100℃ for 60 min. The optimum conditions for HPLC detection step is at the lution rate of 0.6 mL/min with 0.005 mol/L sulfuric acid by the column Bio-Rad Aminex HPX-87H under 55℃, and the xylose content was quantitatively detected and calculated according to the external standard method and peak area integration. The repeatability and accuracy of the SAH-HPLC method was tested for some XOS product determination. The result showed the XOS content was 39.94% in the product at a good repeatability and accuracy and the standard deviation of 0.36%.