Objective To improve the accuracy and reliability of the titration method for determining the peroxide value in rapeseed oil.Methods The peroxide value in rapeseed oil is determined using the titration method, and a mathematical model is established to analyze the sources of uncertainty. The uncertainty components are evaluated, and the combined uncertainty is calculated.Results When the peroxide value in rapeseed oil is 0.043 g/100 g, the expanded uncertainty is ±0.001 06 g/100 g (k=2).Conclusion The factors that mainly influence the uncertainty of the measurement results are the repeatability of sample measurement and titration volume. Other factors have a relatively smaller effect. Using high-precision Class A burettes and increasing the number of parallel measurements can reduce the uncertainty of the detection.