Abstract: The Uncertainty assessment aspect of HPLC determination for benzoic acid content in Harpadon nehereus Hamilton (Bombay duck) has been established, with dispersibility of observed value has been reasonably endowed. In accordance with the criterion JJF1059—1999, instanced by the HPLC determination for benzoic acid content in the fish, factors producing uncertainty during the measurement procedure were analyzed, the uncertainty component were evaluated, the uncertainty of synthesis criterion was assessed, 2 factors contained (P=95%) were taken, to calculate the expansion uncertainty, and report the measurement result by uncertainty. The relative expansion uncertainty of the method was 2.6%. The sample measurement expansion uncertainty was 0.022 g/kg, with a measurement result of 0.87±0.02 g/kg. The assessment aspect is also workable for the uncertainty assessment of HPLC determination for other ingredient contents in edibles.