Objective To develop a high-performance liquid chromatography-based method for the determination of L-threonate in magnesium L-threonate products.Methods The samples were dissolved in water and separated by C18 reversed-phase chromatography with 0.1% phosphoric acid solution and acetonitrile as mobile phase. The flow rate was 0.8 mL/min and the column temperature was 40 ℃， detection was performed at 210 nm using a diode detector.Results The linear relationship between the reference materials of L-threonoid acid was good in the range of 20-500 μg/mL， and the correlation coefficient was r²>0.999. The limit of detection was 1 g/100 g， and the limit of quantification was 2.5 g/100 g. The relative standard deviation （RSD） of intra-day precision and inter-day precision was 0.10%-0.19%， and RSD of the reproducibility was 0.25%-0.40%.Conclusion The method has the advantages of high precision， good stability and simple operation， and can meet the requirements of quality control of magnesium L-threonate product.