According to GB 5009.28 2016 "National Standards for Food Safety Determination of Benzoic Acid, Sorbic Acid and Saccharin Sodium in Foods " of High Performance Liquid Chromatography, established an uncertainty evaluation method for the determination of benzoic acid, sorbic acid and saccharin sodium in Areca catechu L. by HPLC, comprehensively investigates the sources of uncertainty in the whole measurement process, and analyzes and quantifies it. The expanded uncertainty of benzoic acid, sorbic acid and saccharin sodium in the sample is 0.004 10, 0.030 7, 0.200 g/kg, respectively. The main source of uncertainty for the detection in Areca catechu L. is the fitting of the standard curve.