Objective To improve the detection result accuracy of the fluoride content of brick tea.Methods Brick tea is taken as the research object to evaluate the uncertainty of the fluorine content of brick tea by the fluoride ion-selective electrode method according to GB 19965—2005 "Fluorine content of brick tea", CNAS-GL006 "Guide on Quantifying Uncertainty in Chemical Analysis", and JJF 10591—2012 "Evaluation and Expression of Uncertainty in Measurement".Results Under the 95% confidence interval, the fluoride content in brick tea is (281±17) mg/kg, k=2.Conclusion In fluorine content determination by the fluoride ion-selective electrode method, the primary source of uncertainty is the use of the pipette during standard curve configuration.