This standard specifies a method for the determination of boron, aluminium and nitrogen impurities in silicon carbide single crystals using secondary ion mass spectrometry. It is suitable for the quantitative analysis of boron, aluminium and nitrogen impurities, and the determination range includes boron content not less than 5 × 10 ¬ cm ³, aluminium content not less than 5 × 10 ¬ cm ³, and nitrogen content not less than 5 × 10 ◕ cm ³. The method uses high vacuum conditions to bombard the surface of the sample with primary ions produced by oxygen or cesium Ion sources, sputtering secondary ions, and using Mass Spectrometer to separate and record the Mass charge ratio of these ions, thereby calculating the concentration of the element to be measured in the sample. This technique enables high-precision determination of trace impurities in silicon carbide single crystals.