Abstract: In order to verify the reliability of the method for detecting the contents of lead (Pb) in tobacco material of heat-not-burn (HNB) by graphite furnace atomic absorption spectrometry (GF-AAS) and the accuracy of the results, the measurement uncertainty was evaluated using the "bottom-up" to analyze the source of the uncertainty and the influence from uncertainty components. The results showed that:the content of Pb in tobacco material of HNB was 2.02 mg/kg, and the expanded uncertainty of Pb was 0.26 mg/kg(k=2). The standard curve fitting process and the stability of the instrument were the main sources of uncertainty. Adopting an appropriate experiment scheme and reagents, and setting the appropriate instrument parameters can ensure the accuracy and reliability of the results.