According to GB 5009.12—2017, the content of Plumbum was determined under intermediate precision condition of measurement,and the accumulated data was statistically analyzed based on the top-down control chart method. The superposition chart of the value x and EWMA and the chart MR showed that the results conformed to the assumption of normality and independence. The uncertainty of Plumbum in scallion was 0.20 mg/kg.