The peroxide value and acid value in edible vegetable oil were determined by automatic potentiometric titration. Through the establishment of uncertainty mathematical model, the uncertainty components and expanded uncertainty affecting the peroxide value and acid value measurement results were analyzed and calculated. The test results showed that the average peroxide value of the edible vegetable oil was 1.22 mmol/l, the average acid value was 1.43 mg/g, the expanded uncertainty of peroxide value was 0.016 mmol/l, the expanded uncertainty of acid value was 0.044 mg/g, the confidence factor k = 2, and the repeatability of measurement was the main factor affecting the uncertainty of the test results of peroxide value and acid value.