This standard specifies a method for the determination of copper content in antimony and antimony trioxide by flame atomic absorption spectroscopy (AAS), which is suitable for samples with a copper content in the range of 0.0002% to 0.30%. The standard describes the specific steps in the sample dissolving, impurity removal and measurement process. Absorbance of copper is determined in an air-acetylene flame to ensure the accuracy of the measurement. This method effectively eliminates the interference of Miscellaneous impurities and provides a reliable basis for the analysis of copper content in antimony products.